I think you will find that even if you turn everything off, there is still going to be a small load on your batteries that will drain them. On my motorhome there are gas monitors, Smoke detectors, exhaust fans (that turn on and off automatically) and even battery\water\sewer gauges, that stay on all the time unless you remove fuses or turn off breakers.
On my motor home it is easier to access the batteries that the circuit breaker, so that is why I disconnect the ground wire.
I find it easier to disconnect also.
get a bigger solar panel?
even if you have it plugged into shore power you will have to fill the batteries with water.