A truck bed camper will typically have a hardwired 7-way cable that plugs into the 7-way socket in your truck. If you were wanting to remove the hardwired cable from the camper and install the RoadMaster 6-Wire Trailer Connector # RM-910030-7 on the camper you could then use a 7-Wire to 6-Wire to connect your camper to the truck. If you'd prefer a bundle of both components then I recommend the Roadmaster 7-Wire to 6-Wire Flexo-Coil Kit # RM-146-7.
If your camper setup differs then just... view full answer...