My mate Big Al paddles a gen 3 V10. The fit is fine. Epic buckets are shallow, so fit usually isn't a problem. The Kayak Centre Zeplin is the best boat for the larger boned gentleman ever built, however they are impossible to find. The big fella reckons if he paddles a Fenn he needs two.......one for each butt cheek.
He has also paddled Stellars with no problem. Older versions tended to have bigger seats. The gen 1 SEL was a very underrated ski. Nice mix of stability and speed.
Can't help with the clothing. Water is relatively warm, even in winter, so tend to wear a rash vest year round.
Current: NK Storm 61, Kayak Centre Zeplin.
Past: Epic gen3 V10, Fenn Elite carbon, Fenn Elite Vac glass, Fenn Elite SL, Gen 1 Stellar SEL ultra, Epic V10 gen 2, Carbonology Vault, Fenn Swordfish, Red7 pro 70, Think Legend, Red7 60, Fenn Xt.