If the boost solenoid is the same one used on many Class C rigs, they are notorious for failure. They click, and appear to work, just don't pass current because the contact plate is burned up. The solenoid closes every time you start the chassis engine, to allow charging of the house batteries. If you start the engine with weak house batteries, this puts a real heavy load thru a solenoid not designed for that.
I replaced my original boost solenoid with a Cole-Hersee 24213 which is 200 amp rated with silver-tungsten contacts, instead of the <100 amp rated one with its burned up copper contacts.
You really need to be near an electrical outlet to put a regular battery charger directly on the house batteries to recharge them. Then troubleshoot what is killing them.
Charles