There are several parasitics that draw down your batteries, some not easy to find. Put a cutoff switch between the bat and the camper and leave it off when not in use.
My outside entertainment center radio, tv signal amp, co2 detector were depleting my 2 batteries in 3 days. I installed a 4 way marine battery disconnect switch [bat#1, Bat#2, both or OFF] which cured the problem. I now have 24/7 solar and don't worry about turning anything off. Batteries never drop below 12.8 vdc. They generally stay around 13.8vdc.
2013 Silverado 2500 HD Duramax/Allison Tuned
Aviator Wright Flyer #1919
"First In, Last Out". 11B4Y
DAV, MOPH, VFW, 5/7 Cav,1/8 Cav Assoc.
11th ABN Pathfinder Co. N7MIP