I put together took kits based on the types of repairs or adjustments that I will want to be able to do on the road and not ones where I will be wanting to go to a repair shop. If a door latch breaks or a tail light bulb burns out or a fuse blows I want to be able to do a repair quickly and easily.
For emergency repairs I carry duct tape, electrical tape, bailing wire, hose clamps, and bungee cords in a variety of lengths. I also have for years put a small tube of radiator stop leak in the glovebox of all my vehicles as it really does work and can be a real trip saver as well as money saver.
I always have a small hammer, vise-grips, screwdrivers, needle nose pliers, channel lock pliers, wire cutters, box knife, a %' and an 8" Crescent wrench, and a compact hacksaw. The vise-grip pliers and the 5" Crescent wrench are must have items I put again in all my vehicles. Three times I have removed the battery cable on my vehicles or someone else's and avoided an electrical fire. The tool box is roughly 16" x 7" x 7" in size so it does not take much space.
I buy a plastic tool box and put in the tools for the kit and it is separate from my home tools. The quality does not need to be as good and the additional expense of a dedicated set for the RV is trivial.