Three things? A good insurance or road service card for TV and toad brings peace of mind, prevents a sore back,and can really benefit the wallet. Along with a basic tools, we carry a pex crimping tool, 1/2 cinch rings, a variety of fittings and short pieces of pex pipe. Simple plumbing repairs can can get frustrating, if not expensive. We also carry a battery powered drill, bits and drivers.
When we camped/fish/hunted the boonies with a slide-in, we carried a full work shop including log chains, jacks, you name it. DW questioned why all the stuff and no place to sit. We were once 35 miles plus back in on logging trails in Canada. While backing up in a grass field (with one short stump), we (I) badly bent an axle on a boat trailer.Damsel was definitely in distress. I used the log chain and a bottle jack to pump it back straight-it saved the trip. DW still reminds me of that one. So, basically, it depends on your travel and skills. Camp ground, keep it minimal-off road, one of everything hopefully is enough.