After sending my daughter to school for 4 years I have come to the conclusion that we, as parents, tend to analyze and put more thought into all these concerns than the kids ever would.
If he says he won't be claustrophobic, that issue is dead. If changing the sheets isn't a problem to him, believe him, it REALLY isn't a problem.
If someone is going to sit on a bed, I guarantee you he won't care which one.
If they want a folding chair, they will simply find one very easily.
LOL, when my daughter went to school I overthought everything, very very little of it was necessary.