C.O.
the morning erection has NOTHING to do with being circumcised or not. It is a fact of life - it happens.
My 9 and 11 year old wake up most mornings with one - I notice because their PJs are "tented" (LOL). I don't make a big deal of it and just press on.
If you can trust him to NOT pee or poop on the floor, then let him run around in his birthday suit.