@russelltomkins I think this is the GitHub commit for unlimited https://github.com/blynkkk/blynk-library/commit/cdec83ced5efbd3de00a8552787fd25dc0333333 following discussion in this thread Use webhook to PUT data to google sheets?
See comment around number 42 by @vshymanskyy which reminds you to ensure SENDBYTES is big enough when sending unlimited parameters with virtualWrite(). READBYTES will need to be big enough for Webhook reponse.
Please note that I have pushed a new feature - unlimited number of parameters for setProperty and virtualWrite!
__Don’t get excited too much - there’s still limitation of BLYNK_MAX_SENDBYTES 
(but, you can adjust it)._