Johnny,
Before the depression, I ran a yacht maintenance business and we saw this kind of things all the time.
First - You are laboring under the preconceived misconception that a few hours of engine alternator will recover a bank that has been discharged to 50% or less. Sorry Guy, But it actually takes about 6~8 hours of charging to recover a bank that is that gone. No Way Around It. It takes time. More amps available won't help. If you boost the battery terminal voltages enough to get them to charge faster, the heat will damage them.
Second - You do not have enough house bank to run your heat more than one night even if all the things are off. Your computer probably runs at about 5amps. That alone will take the little house bank you have off line in 8 hours.
First a caution: try to avoid parallel batteries. It just doesn't work out in the end.
If you could find someplace inside the coach to put a pair of gold cart batteries, that could get you though the night. Until then, you better plan on running your generator all the hours you are awake. Can put them out on the bumper, but if it is the coach in the picture, that much weight all the way at the rear may not be good. If you do have to put batteries outside, make sure that the lock real well.
I wish you luck.
Matt
