gbopp covered the registration question.
As far as insurance goes, it depends on two things. If you unload it at a campground, then at a minimum I would get liability insurance in case someone gets hurt playing around or under it.
If you don't unload, I would suggest you contact your truck's insurance company and ask specific questions in regards to liability and comprehensive coverage while it is on the truck and off the truck at your house or storage facility.
In regards to comprehension coverage, I wouldn't insure it because they won't pay very much for a 17 year old camper. However, if you can't afford to buy another one if you don't get something, than insurance may be for you.
Some companies will cover it by just adding a rider to the truck policy for not much money.
I never unload on the road and can cover the $5k my camper is worth in the unlikely hood something happens to it so I don't carry any insurance.
