Not sure I'd make the entire guitar fretless - it would be like trying to play an -out-of-tune guitar....maybe a bit of fun for a few minutes but a bit irritating thereafter?

I'd consider fretting the first 7 or 8 and fretless thereafter - that way you have all the fretless notes on the lead and can still play a proper chord without making anyone cringe in horror!

https://www.youtube.com/watch?v=ewCZ-TWdx40