The first TV segment I did was on this topic- essential tools for an RVer, regardless of technical competence.
Multi bit driver, with assortment of bits, including the #2 square.
Pliers.
Vice Grips,
Adjustable wrench (large and small).
Utility knife.
12 volt test light.
Plug in outlet checker.
Multimeter.
Hammer.
Bigger Hammer.
Optional- if you own an Airstream- pop rivet gun.
Consumables:
Spare fuses.
Spare bulbs,
Hose washers,
Duct Tape,
Electrical tape,
Nylon wire ties,
Spray lube,
Silicone lube,
Penetrating lube.
While I was traveling, for a while I had a full shop in my truck (cube van), but still kept the proverbial kitchen drawer with basic tools in the trailer- don't want to have to dig out the big tool box to tighten a screw.