Another vote for on board air. I've become a fan of a CO2 tank for big needs (filling tires, running air tools). Add a small compressor if going ARB.
There are so many uses for air. Mostly airing up to drive home. Running an impact wrench for the tire change. Add an air nozzle for cleaning, drying ignition parts as well.
Trail welder. There just isn't much demand for it. It is fairly rare to have a failure that can be welded to get you home. You are not going to fix a busted U-joint with a welder. Clogged carb passage, not a welder but compressed air can work wonders on that. Track bar torn off? I've seen a couple of ratchet straps used to keep the axle located enough to get off the trail. Not to say there isn't any demand for it, there have been some trail repair done with welders. And typically they are scab jobs just to get off the trail.