Not without Internet access on the Blynk server.
You could fix remote access, but as @Jamin stated, you need Internet for that. If you have a local server in the RV you can use services like DynDns to have a fixed DNS name to which you can connect to your RV. It has to have power though and Internet.
This is where having a cellular based connection might be better than traditional ISP/WISP, assuming RV travels a lot. Although I also recommend a local server/self contained WiFi network with the cellular link being on the router’s WAN end
Not a GSM based MCU device - that would also work, but requires Blynk cloud or cloud based Local Server and would shut down the RV’s Blynk system if in poor cell area.
If you wish to actively pursue this, then open your own RV topic (if you haven’t already) and we can continue over there, so as to not overly bloat someone else’s Projects made with Blynk topic.
EDIT - I found your topic… perhaps a better title? 
EDIT 2 - I just moved relevant posts over here. Easier this way 
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Here is a more pricey option… but would probably work out cheaper than leaving your RV connected via GSM 24/7.
GSM wouldn’t be needed 24/7… just for occasional internet connection… all the Blynk stuff, devices, server and router, would be “closed circuit” so to speak and could run 24/7 on the 12v DC coach system of an RV (alternator and solar charged deep cycle batteries).
If parked off grid, then GSM, if at a RV site, many have WiFi and as @Lichtsignaal mentioned, some form of dynamic DNS service would be necessary anyhow for “remote” access to your RV when away from your home away.
I’m no RV expert here but in my mind I imagined the RV parked up at a beach or lake without a WIFI hotspot around.
Then you would need the Blynk Server to have internet access of its own via GSM… but then say you leave to go have dinner at another RV down the end of the beach…your RV would need to stay connected to the internet via GSM just waiting for you to access blynk to check if the door is still closed. That is using data, albeit a tiny amount.
But then again… im no expert in RV lifestyle 
OHH why not just buy a cheap second phone and set it up as perminent hotspot and have the server connect to it for internet 
That’s what I meant when I said the router would utilise GSM or park WiFi or mobile hotspot, etc. on the WAN side.
Besides, Local Server on an RPi in the RV connected to the router, supplying local WiFi to all the other devices scattered around the RV, wouldn’t need internet except for remote monitoring. Just program it well for autonomous functionality 
Us RVers love to go out into the middle of nowhere and curl up to a… large screen TV and watch netflix 
I used particle electron to control my car from anywhere coz it has SIM card 3G internet that allow u to connect to blynk cloud. Also it a cellular as GUNNER said But u will have to pay monthly 2.99 for the service or use third party SIM card am using AT&T I had it extra .
Just another option for u
Thanks
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Oh man im totally going to try and go the particle electron route, that seem awesome.
Ok now that I have my connected option of using the particle electron. I need help setting up the right gear.
What hardware would I need to get started on this idea?
I can run wires to any device now but would like to scale the idea for others and have different “Modules” that wirelessly connect to each other like the Mesh IOT.
Remember, the Particle Electron is just one device… you will probably need many spread out in the RV, each controlling a few sensors, relays etc. Try to keep the in RV infrastructure running on it’s own WiFi network and a Local Server, that way everything runs with or without internet. And if you opt for a cell based internet connection to feed the router, then you only need one account and only use it (and pay$$) when internet connectivity is required.
Well, if you are really gonna do this it’ll be a nice investment to make life more easy on the road. I’d start with making some sort of list of things you want to achieve and some schematics of where you are gonna place different senors, relays and so on. Just to get a good overview.
I started a list when I started the post above
For a project of this size I would rather use plcs or microplcs. These have the certifications needed to keep the installation legal and safe. They meet fire and safety standards, they have integrated local webservers with safety. Even something as cheap and small as a LOGO 8 has a webserver. You can run everything locally using your phone as a web browser. You have 12V versions, 24V versions. And if connecting an I2C sensor is a must you can make a really cheap gateway using a microcontroller and some ssr to make a cheap i2c to pwm signal converter. If you like remote managing you could integrate sms gsm gps module. Also if you create a local wifi network and connect to the internet you could reprogram the rv off site. Setting a local server and have it run consistently is not so easy. If the degree of uptime is something that you need I really recommend using a somewhat industrial solution.
Compared to a half dozen Wemos or NodeMCUs a single RPi and Blynk, I would hardly call them cheap
RV’s are expensive enough without using industrial grade toys in a DIY project… and since they don’t support Blynk, I don’t think @jhiner1978 would get as much assistance here on using them
I setup my Local Server in about an hour (with no prior Blynk or Linux experience) and it has been running 24/7 since November 2016.
Not knocking PLCs or quality toys, they have their place, and If I was manufacturing IoT RVs or professionally customising them, then perhaps (with a service contract to go with )… but DIY is about, well doing it yourself… low cost, lots of peer support and fun 
This is definitely what I’m trying to achieve here. Just need help picking out the right boards, servers, devices to make it work. Thanks
I would suggest starting out with a handful of different boards; Wemos, NodeMCU, generic ESP8266, etc… play around with them on the workbench with various sensors and relays and learn what works best for you.
Then graduate to Local Server and it’s various options and such… there is an article around here somewhere on using a RPi Zero WiFi as such a standalone server and access point.
Found it:
I think I’d go for a Raspberry Pi running Node-Red and MQTT as the core of the (mobile) home automation system. An internal Wi-Fi system would give you the means to connect wirelessly to ESP8266 devices that are physically connected to sensors and actuators. I’d go for nextion displays as the primary way of controlling heating, ventilation and environmental monitoring systems so that the system wasn’t reliant on the use of mobile phones or tablets. You’ll probably find that non-techy members of the family will find it easier to interact with a fixed display rather than having to find the right app to turn the heating up.
I’d then use Blynk integrated with Node-Red (very easy to do) so that when the RV has internet access I could remotely monitor water, temperature and power levels etc. from a mobile device.
If I needed remote access in more situations I think I’d add GSM or SMS to the equation.
If you feel that you need to use Blynk while you’re in or around your RV then you could add a Blynk server to the equation.
I’d certainly steer clear of Bluetooth. While it has its uses, I don’t think it’s great for this type of situation.
Pete.
Here is an update on the project thus far
I got a raspberry pi zero w and on the pi, I installed the script
I also have the local blynk server running on this and static IP address etc…
I also got a bunch of these to use as my switches
https://www.itead.cc/smart-home/sonoff-sv.html
I also have a nextion display (I figure I could add this last after everything is working)
Then I flashed all of those with tasmota
But now I’m not sure where to start. What are my next steps? Thanks