My last two trucks have been ordered with dual alternators (Ford and Ram). Unless you have dedicated wiring run to your camper, you will not see the benefit from buying two and I question whether you will even see a benefit from an upgraded single.
I have a constant duty solenoid triggered by an upfitter switch to heavy cabling running to the back of my current truck. My setup is little different with a flat bed and storage boxes than a pick up, but this might give you some ideas:
In my lower truck storage boxes I have two banks of batteries that are tied to the truck charging system, to the truck camper and to a third bank of batteries on my enclosed trailer. Interconnects for the camper and trailer are large diameter Anderson 2-pole plugs. All three banks of external batteries can power the camper and all four banks of batteries can be charged via truck, camper generator, camper solar or campground electric.
I used the connections to the heavy lines in the camper running to the generator starter motor as my tap to the external interconnect Anderson plug. All sources of power have a resettable circuit breaker if there is any short or overload condition.
