Didn't read all the replies, but have had stuff happen out in the mountains. This year the hydroboost started leaking, but it looked like the transmission (fluid all over the trans lines and it was trans fluid). Luckily we got out and back to town ok without incident. Was concerned we'd loose power brakes given we were toying a toy hauler. Got the hydroboost replaced by a local dealer and ended up having brake issues the next weekend, again while towing the camper. Brakes locked up and the Cummins could not move the truck. I ended up figuring it out...they forgot to put a plate back between the hydrobooster unit and master cylinder. Was able to fix it out in the field with basic tools, but shouldn't have had to.
Taking two vehicles is usually our approach. Sure, costs more in fuel, but then we have a back up just in case. We're often well out of cell service. I worry about the SXS or ATV not starting or breaking down, getting a flat, etc. Again, we usually travel in pairs, or at least know where everyone is going for the day so if someone doesn't show up, we know where to look. We use the SXS/ATV's to travel from camp to hunting spots and can get 15+ miles away from camp, easily. These machines also serve as a safety vehicle if we only take one truck...we can always ride out and get help.
Basic tools (sockets, wrenches, etc) are always with us. Can't fix everything, but we try to travel prepared. Being handy with the tools is important, seems to be a lost skill these days to diagnose and repair stuff in the field. I hate the electrical tech packed in vehicles for this reason.