extra propane tanks. you never know when one will run out.
also, a small burner attachment for a standard propane tank is cheap and small, and can be very useful if you’re not where you can hook up power.
jugs of water, just in case you can’t hook up, or the water is total crap.
consider helper springs for your vehicle.
fire starters and a camp fire ring- if you like camp fires.
bug spray and sunscreen- it’s one of those little things you always seem to forget to pack.
shovel, bow saw and axe should be part of your tool kit.
oh.. electric brake module for your truck if there isn’t one built in. very important.