I've built them platform and a bench,having problems finding a pan 36x50 if I lose the bench 36x39. Weird sizes I know!Any thoughts advice.Thanks for platform advice.This is a up flush install.

Kerdi-Schluter systems work in all applications... it's the bench work that you will need to be very careful with. Here, if possible, I would build that platform full size and then install a BETTER BENCH... check them out @ Better-Bench | Innovis Corporation

I would also strongly suggest looking up the kerdi-schluter system on YOUTUBE... they have many great videos that should help you greatly here!

Good luck!

Mark