I think everything sounds fine, 35/36" scale would probably only make things slightly tighter. The only issue I can see is with the 36 (or more) frets. as you get up around the 3 octave mark there ends up being VERY little distance between the frets. So in the upper ranges your fretboard will end up being more of whatever they fill the slots with than whatever the fingerboard is made from and may make it a VERY difficult job (so if you were to continue I would ABSOLTELY recommend having it done by someone who's done lined fretless boards before, this wouldn't be MY choice for a first try.) But you will also have a very difficult time distinguishing the upper register frets, there will be nearly no space for marker dots and your fingers will probably be hitting over a 3-4 fret span. Your ears will be closer to telling if you're in tune than your eyes will be.
(here's a photo of a Conklin G*!@r with a 3 octave fretted board, It's a fanned fret, but you can see how close the frets have become and also see at the 3 octave part how little difference there is between the longer and shorter scales...)
A longer scale doesn't make much of a difference since the frets change at a fixed ratio of the scale length (i.e. a longer scale has frets farther appart at the start than a shorter one, but they also change distances at a greater rate)
It can be done, I'm just not sure how useable the lines would be tho.
