Welcome to iRV2.
Sorry your first post is about problems .
JMHO: Loss of 12 volt power and then back without any change but removing load from the system , would indicate a bad connection on the power side , that overheats/opens then cools and reconnects.
Start at the batteries and remove and clean/re-connect . Follow the positive cable from the batteries and look for a 12 volt self reset circuit breaker , that may just be doing it's job , or tripping at a way lower load than it's spec'd for.