From the  cheap rv living forum is a list of recommended automotive items to have on hand:

2 x each fan belt
1 x each hose (ALL OF THEM!)
1 x each hose clamp (ALL OF THEM!)
2 x cans of flat fix
2 x quarts of oil & trans fluid
1 x can of brake fluid
2 x spare stop/turn/brake light etc. bulbs
2 x assorted fuses kits
Water (for radiator if needed, your drinking water works fine.)
TOOLS… (including duct tape, rope, twine, bailing wire etc.)

(I didn’t mention the obvious like a jack, a spare tire, a tire iron, flashlights, gloves, etc.)

This seems excesive in a vehicle with under 50,000 miles. Maybe not.