burlmart - I used the emergency start switch once when the coach battery was low and the boost from the chassis battery fired up the generator. I am not sure that it would work the other way around - dead chassis and a good coach battery.
Daniel C. - Have you ever used the emergency start switch when the truck battery was dead? As for the power consumption, I visualized needing the 1000 watts or so for maybe popping popcorn with the microwave for a few minutes. Maybe watching TV for an hour or two - but that only needs 150-300 watts or so. If driving down the road, it would not be a problem. If dry camping, then might need a boost from the other battery.