Motorhome won't start

I don't know if the Aerbus is set up the same as ours, but we have a 1999 Rexhall Vision which we bought last year. On our first trip out, we drained the house batteries, pdq. We happened to be near Lancaster CA and stopped in at the factory. They told us someone had put start batteries in for house batteries, so they swapped them out. Within two weeks we had the same problem of the house batteries draining (we'd been parked for a week and started the generator occasionally to keep the batteries charged). We were in Custer, and managed to hook up with a very good mobile technician. He diagnosed the problem in about 10 minutes - on our dash there are three switches, two are rockers and one is a momentary switch. The momentary is to start the generator, that was pretty obvious. The middle switch is for the little dome lights on the driver and passenger side, and the switch on the far left is to start the motor with the house batteries. What we didn't know is that it has to be ON while driving in order to keep the house batteries charged. I understand that in some rigs the alternate start switch is a momentary switch similar to the generator switch. The stairs are supposed to retract when the engine is turned on - sometimes ours don't retract fully, but it doesn't seem to lock out the engine. We did note that the chassis battery will go dead quite quickly from just sitting in the driveway, so we installed a trickle charger, which we can plug in under the dash when we are on shore power.
We were on the road for just over 6 weeks (just got back) and had no battery issues. We did blow a spark plug on the V10, but that's another story altogether! I hope you enjoy your Rexhall, ours is great!