What the electrical connection between the camper and the truck provides is based totally on the type of camper. There is no standard connection for TC's.
A true camper shell may only need a two pole plug providing +/- 12v DC for a single interior light. A truck camper that doesn't extend past the end of the bed, and doesn't cover the trucks brake and turn signals, may only need +/- 12v DC, and possibly a connection to the truck running lights. A bigger TC that covers the brake and turn signals would need +/- 12v, L and R turn, brake lights, and running lights. That's what my TC has in it's umbilical cord, and I would use 6 of the 7 pins in an RV plug.
Due to (relatively speaking) how much closer TC's are to the trucks alternator, they are in a unique position to having a very robust battery charging system if the owner is willing to put in a little work. Several TC owners here (myself included) have run much heavier gauge wires from the truck alternator to the TC battery so that the battery will charge up much faster than through the OEM circuit that runs through the standard RV plug in the bed or under the bumper.
Due to the higher amps involved, the heavier gauge wires will need to be run through a different style plug than the RV seven blade plug. Some use Anderson power pole connectors, some (myself) use a Pollack seven round pin plug set close to the front of the bed that can handle the larger wires and higher amperage.
Some will split the umbilical into two cords, running the +/- 12v through 4 gauge wires and a Pollack two round pin plug that can handle up to 200 amps, and the brake, turn, and running lights through a four pole plug. That's what I intend to do on my new truck.
The +12v wire will be run directly from the back of the alternator, through a continuous-duty solenoid controlled by one of the upfitter switches in the dash and a re-settable CB of the appropriate amperage, to the two-pole connector in the truck bed. The -12v wire will be run from an appropriate ground point near the alternator to the two-pole connector in the truck bed.
:):)
2001 Lance 1121 on a 2016 F450 ‘Scuse me while I whinge.
And for all you Scooby-Doo and Yosemite Sam types………..Let’s Go Brandon!!!