I used to do that but now I use a small tilt trailer that...... makes it much easier to load and unload the bike...…. and to haul additional items like a generator and additional bikes when necessary.... and to get in and out of the camper if it has a rear door.....there is also the concern about the levered weight of the bike and rack on the PU's rear suspension , tires and the center of gravity of the load .... the trailer is un sprung weight that has no effect on the hauling capacity of the PU....the trailer being a small part of the towing capacity...yes, I know a trailer can often be a pain in the ass.....and needs to have tabs and be maintained.
I suspect that a majority of pickups with campers are overloaded as it is...