[DAF]

Normally 2 batteries connected together (in parallel) will have an internal current flowing between the 2 that will eventually cause a full discharge. To avoid this as much possible the batteries need to be the same type, size and age as well as having the same state of charge to begin with. It looks like you already have that. Besides the interior/exterior lights and water pump, and furnace fan, your RV does not have many other heavy users that come standard. The electronics in the fridge don't use much. Your brakes should be isolated when you are not towing. There is also the CO/Propane detector alarm which needs some juice. What additional appliances do you normally use? The only way I know for you to pin down the culprit is to disconnect or turn off all 12v loads and take a current reading at the battery(s) as you connect/operate each one back. By the way, the current should be zero with everything disconnected/off. If not , that indicates internal wiring leaks. Good Luck!