Off road boondocking types will obviously need a more complete rescue kit than those who seldom leave the highway, state parks, rv parks type of travel.
I recently needed to replace a fuel pump inside a 34 gallon fuel tank. Fortunately I had a friend with me who lived only 50 miles away just out of the forest. You can plan for a lot of stuff but not this fix. We needed 5-5 gallon cans to siphon all the fuel into before we could even think to do the job of removing the tank and replacing the internal fuel pump after about 150 miles total driving to get tools and parts.
I bring a set of metric and standard tools, wrenches and sockets plus a bunch of other more specialty tools that I've accumulated over the years fixing the little surprises as the occur. Bottle jack is handy, an aluminum floor jack is better. If I need additional lift, there are the wheel blocks and ramps in the TC.
Some things you can plan for but the job may be just too big for in the field. You can't haul an entire parts crib with you so you have to pick your battles.
Make sure your radiator hoses are good, not too old, especially if you go miles out into the boonies.
Check your spare tire. Be sure it's of the proper load rating and in usable condition.
I just installed new shocks and inspected the underside for anything lose, rubbing, come apart, missing.
I just installed new disc brake pads, all 4 wheels.
One thing I do carry is a spark plug blow out retrofit repair seat, high temp red thread lock, and the H1 or whatever special spark plug for the repair.
I carry my old serpentine fan belt as a spare. I should carry a spare tension roller since that has gone out unexpectedly before.
Another thing to have is an emergency couple hundred dollars cash for those unknown situations.
Plan ahead and fix it before it needs fixing. Preventative maintenance has it's advantages.