Another option - is to physically disconnect the battery using a quick disconnect or
battery isolator - I've left mine disconnected over winter and spring in the Scotland (4 - 5 months) and started first time when reconnecting the battery - just make sure you put fuel stabiliser in the engine before laying it up.
Then use
a battery isolator switch to use only the starter to start, then recharge it, then recharge the house battery from the alternator.
You can use
a battery isolator - check at places that sell equipment for RV's.
The bonus feature of
a battery isolator is in winter if you a little juice to crank over - just use a single battery cable short the right and left terminal and jump start your vehicle.
A battery isolator is a device with 2 diodes inside.
maybe a extra battery in the trunk with
a battery isolator might be what the trick.