Since the house batteries are one alternator, the chassis on another, they have no contact with each other. I plan to keep them this way, just so an electrical fault with the RV part won't affect the engine or drivetrain.
Catastrophic fuses go without saying. I like having those on all the main paths, just so that a short doesn't mean a swath of pure destruction.
00 wire makes sense, I was even thinking of 000 wire, just so voltage losses are minimized.
As for load, at idle, the secondary alternator sits at 160 amperes, so it isn't too much drag. It is present, but it isn't anything out of spec for the engine.
This is for a custom class "B" motorhome, and 500 watts of solar will be difficult to place on the rig, unless I go with a portable solar rig, which I don't really have room for.
