Beware of disconnect switch amp ratings! 12v is not the same as 24v rating.
I am with DrewE. Alternative is to maintain the engine battery from the house battery, but ISTR yours are 24v so another way is to use a small charger on the engine batt if you have shore power or solar "maintainer" if you have any sunshine there.
If you do have a way to use 12v from the house (tap in to one of two 12s in series?) or a DC-DC converter, then you can use a trickle start type to maintain engine from house.
I have two ways--on solar to house 12v, I have an adapter that goes from the 12v socket in the TV panel (house) to the dash cig lighter socket (engine). OR, I just use a 12v maintainer charger to the engine batt when on shore power.
