Don't carry more tools and parts than you are comfortable doing. Even then one can overdo it.
I do long-distance bike camping myself, but my tools are rather thin because I do a very extensive pre-ride inspection before I go, and do one every morning. But this is a practice I've done for the last 50 years, about 40 before I started multi-day trips, and I've never had a mechanical breakdown on the road, not including flats of course. Every morning, I go through my water bottle cages, fenders, and pannier racks to make sure the bolts are tight, those things seem to be the most likely to loosen, but so far they haven't.
What I carry is a Park MTB3 multi-tool, a small pair of folding pliers, zip ties, duct tape, and 2 FiberFix spokes, that's it besides the typical flat repair stuff.
The only spare parts I carry is a bolt in case a fender, pannier, or bottle cage bolt comes off I can replace it, and the FiberFix spokes. I do carry a spare tube, but just one.
The FiberFix spokes mean I can replace a spoke or two without removing the cassette, so no tool is needed. However, with low spoke count modern wheels the concern is if I break a spoke the wheel will probably taco and I don't carry an extra rim!
Flat stuff is typical with most riders. I carry a long 11-inch Lezyne Road Drive pump with a hose that has a built-in gauge, so no separate gauge is needed. The longer pump makes it a lot easier to pump with. I rarely get a flat and haven't had a flat on my touring rig yet, but I use higher-end Schwalbe Amotion tires that have the lowest rolling resistance of any touring tire, but they now come out with a tire with even lower rolling resistance called the Marathon Efficiency, so when mine wear out I'm going with those. I do cheat though, I use Clear Motion Armadillo flat liners, they are tougher than Mr. Tuffy and lighter in weight. Of course, I carry patches for the tube and boot patches for the tire, and two spare tubes. I also carry 3 tire irons, two of them are Lezyne XL power levers, and the other is a Kool Stop Tire Bead Jack that I cut off about a 1/2 an inch off the handle so I could fit it into the seat bag. The Schwalbe tires are very tough to put on and the Kool Stop makes it possible to put on the last couple of inches of tire. I use 2 reusable wide Zip ties when putting on those tires to lock one end of the bead to the rim so it won't slide out of the rim while putting the other side on. I have a Presta to Schrader converter.
I decided to go with mechanic disk brakes so there is no fluid to carry or worry about leaks. I'm another person who is not sold on tubeless tires, though the tires on my touring bike are tubeless I use tubes. But I can also fix most flats on any tubed tire without removing the wheel off the bike! It's simple to do if you can find the hole, simply leave the wheel on the bike, then remove half the bead with the hole in the middle, and then pull out about a fourth of the tube with the hole in the middle of the tube, patch like normal.