I don't think 200V per se is that big a headache - though 200V DC can get quite interesting when it comes to handling faults. I also suspect that a fuel cell - perhaps a methanol type - would not be an entirely dead duck. And it's quite conceivable that a novel fuel linked to a novel fuel cell coupled to a modern control system that manages a stock motor could be more reliable than a 40-year old LyConting. But all that new-fangled stuff requires R&D for GA application with certification on top and I suspect that there is your problem.
(It'd be one fabulous PhD project though wouldn't it!!)