Michael,

Make a note of the hours on the generator each time you go check on the bus. That way you can determine how much you are actually using the generator. Also make sure you are not trying to charge the batteries to 100%, that takes a long time. You may be able to set your autostart to run for X hours the shut down. I would recommend 1 to 2 hours each time.

Other then that maybe consider just using the aqua hot and not the electric toe kick heaters. The aqua hot will likely run much longer before the batteries run low then the time the toe kick heaters run. If you do not winterize, you have to keep some heat in the bus. Seems like you have to run the generator once in a while to get it done.