I have both - a regular 7 pin RV connector, and special lance camper plug in my bed. The regular connecter was a kit that plugs into the back of the truck, near the stock 7 pin setup. It has a very light weight charge cable, which you would never ever be able to re-charge a dead battery (too much voltage drop/not enough current due to under sizing of the wiring, and distance)
I wired the lance into a battery isolator up front, direct to the batteries. I also added a 3rd plug, a 200amp 2pin lift plug, so I can also charge dead batteries from the truck (and also run the inverter, using the truck engine as a 12v gennie.. yea, that's a special case)
I no longer have the lance, but I decided to just leave it, in case I'm ever asked to move/haul a lance camper.