Leatherneck1812 here, been RVing since 2001, we’re on or fifth RV (4 travel trailers (TT) and one 5th wheel). Various brands, on the trailers like some, we started small went big (the 5th wheel) and went back to small. What I take when I travel:
2 - Full 5 gallon gas cans. You never know when you need them.
1 - AC air compressor/canister. Many stations no longer have air available, or their hoses or pumps are not operational.
Spare IT equipment cords, one set for the truck, one for the trailer.
A small leaf blower, for cleaning off the awning before rolling it up.
4 - lawn chairs, two for my wife and I, and two for visitors.
Bottled water for us and our two dogs.
A good tool kit ( cable ties, teflon plumbing tape, assorted tools, proper sized socket for the water heater rod, batteries for the smoke/LP detectors, a small electric heater (So you don’t burn your propane), this is (for me the bare essentials) a basic list.