I keep an impact gun, impact sockets, open end wrench set, screw drivers, torx bit sockets, ratchet, multimeter, fuel pressure gauge, vacuum gauge, tire pressure gauge, air hose, breaker bar, screwdrivers, snatch block, tree saver, heavy leather work gloves, PB blaster, paracord, duct tape, maybe some spare wire. and that's about it. Have a good pair of shoes or boots on all the time. If you're missing something, there is an advanced autozone on every street corner. You just may need to hike out of the woods to get to the street.
Just inspect your belts, hoses, tires, bushings, main electrical connections every month or so. And you should be pretty reliable.