My must haves (other than the camper itself)...
My Brinkmann travel propane grill. The wife bought it for me for Christmas back when we owned our Class A Winnebago. It fit in one of the basement storage compartments like it was custom made for it. She didn't measure it. She just got lucky. Now it rides on the front deck of the 21SSL.
And my Margaritaville Keywest frozen drink maker.
If I got those two, I got me a party!