You will be surprised at what you can do when you find yourself in those situations, but that is also why I don't wheel alone.
That is why a parts store is never far away for you, just hitch a ride.
I don't recommend wheeling alone especially
if you are not up to it or capable of it.
If you do, then you already know you have to carry different stuff than people who wheeel together.
Better be able to fix it yourself or have what you need. An extensive first aid kit can help you and your passengers true, but also help someone in another vehicle too, a complete stranger even.
A welder can fix a great many things that break on the trail. If you have welding capabilities, more gear is needed. A hack saw to cut and fit, a file to deburr, a few pieces of angle iron in different lengths and thicknesses, some large vise grips, A compact auto darkening hood is helpful and easy to pack.
A fire suppresion system PLUS fire extinguishers are a peace of mind, fires do one of two things, go out or get bigger, it depends on what you have to fight it. Don't use Halon, ATFF or foam is best, but dry types will do the job (purple K comes to mind). Think it's over kill? Ask a guy in the burn ward if 500 bucks is worth it .Don't want to sound like a bonehead here, I care about you
Co2 is great but what happens when the tank(s) is empty? Air is a big help in the field, a air rachet speeds things up and make hard to reach tasks easier. Bring along a compact mat or small tarp to lay on and/or lay small parts on or parts that need to stay clean.
Just a few thoughts. OP asked, i'ts just my opinion.