Do I need to register and get insurance on my truck camper?

Since the camper has no wheels, and is no more than cargo. You shouldn't need any type of insurance on it while traveling. the truck insurance will cover any thing the truck hits, with or with out the camper on board.

However. IF you are concerned about the replacement of the camper. You would need to get insurance. But you will need to figure out if the cost of insurance is worth the price of the camper. At some point. It does not pay to have collision, or Comp on a item.