Update:
I ended up getting this
controller on Amazon.
Installed it and it seems to working well fixing the overcharging problem.
Floating about 13.5V. It's not an MPPT charger but it had good reviews and shows voltages & currents for
the battery & collector.
I also installed inline fuses on the solar panel and the battery so that I can disconnect everything
during the off season months.
I tried measuring the truck battery voltage and it obviously isn't connected to the camper battery circuit. Does anyone charge their truck battery with their camper collector?
Or is there a problem with the alternator and collectors fighting each other going down the road?