My Torquelift Glo Steps completely obscure my plate, no way you could ever see it unless you got down and looked under the folded steps, why I added a license plate bracket to the bottom of the camper and mount the truck plate there.
After reading along, I called the Michigan State Police and asked them for a verification and the trooper on duty told me if I want to mount the plate in plain sight, Michigan was good with that. We don't have camper registration either nor do we have a front plate. I sure as heck don't want any LE getting his (or her) knees dirty crawling under my camper to check the plate, if, I got pulled over for something which not being stopped for at least the last 20 years is pretty slim.
So, I'll keep my tag in plain sight when I have the TC in the bed and you can do as you wish.
Far as wanting to 'see' in your camper, I suspect the officer was 'feeling you out' to ascertain if you might be carrying something illegal inside. He wanted to see your reaction before proceeding. When he got a neutral reaction, his training told him you were clean.
if I got stopped and an officer want to see 'inside', I'd invite him in for a cold soda.