Definitely interested in any updates you have on how potty training goes!
Our dwarf hamsters have always peed on their wheels
It's actually one of the signs I look for in the morning if I didn't notice them up the night before, and I want to make sure they got some exercise

I appreciate the comment about cleaning it regularly but not overly frequently. Our current hamster will sometimes avoid her wheel when I clean it too frequently (previous hamsters I would clean it every-other-day, but right now I do about once a week unless it is messier than usual).
You'll probably have to follow his lead on what he prefers. Good luck!