Regarding battery boil over, that will indeed depend on what kind of converter is installed in the motorhome. The converters that do not employ 3 stage (smart) chargers are good candidates for causing this problem. You have to keep your eye on the battery fluid level. Once the batteries are at full charge, it may be more practical to disconnect them and only hook up a charger once in a while to maintain them, or keep them hooked up to a trickle charger. This avoids the possibility of a battery that develops a bad cell from damaging your system. Depending on where you are, (IE a cold place or a warm place), it could be beneficial to store them inside over very cold periods. The chassis battery (starter battery) also requires attention as many do not charge from the converter under shore power and could, perhaps, require the addition of a trickle charger to maintain it.
It would also be beneficial to try and figure out what loads are still on when parked like that and disconnect them where possible. Two come to mind, the thermostat and CO /propane detector. Clocks and smoke detectors are likely have their own 1.5V/9V batteries, The radio memory is likely on the chassis battery etc.