I work a lot of shutdowns so I stay in my camper several weeks or months every year. My camper is about 18 feet long. It’s perfect for 1 person working out of town. I always take some scrap 2x treated lumber big enough to put under the wheels for leveling the camper. Extra fuses and propane. Cordless impact with sockets. Teflon tape for the water connection. I use plastic totes for my clothes and store under the bed. A chain and lock to secure propane bottle while in use. Had one stolen before. Pex tools and fittings. Pressure reducer for water line. Always turn off the water heater when not needed. I forgot one day and while I was at work, my neighbors water supply line ruptured. So my tank drained and the electric board burned up. Luckily there were showers at work that I could use until I could fix it.

A good bottle jack and 4 pieces of 2x12 about 16” long in case you ever have a flat on the road

I do. Had mine at Camp Horne.

I have a 20" 6x6 with a bevel cut on one end. It makes a good wheel chock and also can be used to drive the good tire up on to allow for a flat to be changed (with dual axles, of course) but I have a bottle jack as well... just in case.