tire changing tools and a volt meter are a must. the rest you can pick up as you need it. As im loading the camper i grab my tool bag and just load it with everything i think ill need but never use. If im going far from home i bring more stuff. we do alot of local camping so on those trips i just bring the essentials. if ive got a major issue i can run home and grab something.
Most RV repairs at the campsite are with basic/simple tools. wrenches/screwdrivers ect. I keep one of those cheap Christmas gift tool kits in the camper as well. I think the main issue is getting off the side of the road. Have tools for that. the rest can be bought or brought as you need it.