When we got our first camper I did a lot of research and calculations, and ended up with 6 ga. power AND ground wires between the camper batteries and the truck's batteries. That size cable requires a breaker at each battery. I used an MEP Marine VSR to control the charging and isolation. This all worked well, even after I replaced the 3-way fridge with a 12 VDC compressor fridge.
Then I added solar and everything changed for the better. With solar in place it was rare that the alternator needed to do more than just top off the camper batteries when we were out and about with the camper. I even replaced the older, single sensing VSR with a newer dual sensing VSR so that the solar would keep the truck's batteries topped off. All of that from only a single 100 watt solar panel mounted flat on the roof of the camper. A big part of that was our use. Other than the fridge we rarely use the lights or the fan. And that we're on the Lower Left Coastal Desert.
Were I doing it all again from scratch I would go with the solar first, and then assess if I needed the alternator to charge the camper batteries or not. With enough solar power I doubt that I would need it unless traveling out of our normal area.
I also agree with the post above that FB is a terrible place to try to have separate technical conversations, and then be able to find them for reference a year later. FB just seems a lot like AOL was, a place where those who don't know it could be better think that it's the best option possible.
