Ok tried not to bite but had a few drinks and now can’t resist it. Put you feet stance width apart, do 20 squats, if your feet are still 0/0 then feel free to ride 0/0. Nearly everyone else will be duck, so that’s why we ride duck!
I have been fortunate enough to get to a reasonable level (BASI 2), my brother is ISIA and I have been lucky enough to be triained by some of the best trainers in Britain (Ash Newnes and Ben Kinner) they all ride duck, I have seen Ben rip it with no highbacks but I wouldn’t recommend that for the average rider!
To the OP custom footbeds will help, the right boots are key! Good bindings that major on comfort will also help, lessons from a good instructor will definitely help with the foot pain as well as improving your technique and that will most importantly allow you to have more fun!
I have very flat feet and still from time to time get severe foot pain despite everything, it’s just one of those things, take it as an excuse to have a break then come back and hit it hard again.