Ok, here's my list based on a lot of years and several RV's
An RV mat for under the awning, keeps the rv cleaner and makes sitting outside a little more comfy
A small folding table(costco$35.00) for sitting the barbq on and an occaisonal cold beverage
A small grill
A portable small propane tank and adapter to the barbq so you don't have to mess with the green coleman bottles
A couple of good flashlights, 1 for inside and 1 in a bay
stakes/nails for holding the mat down and a stout small sledge hammer for installing them
extra folding chairs(so when company comes over to enjoy your mat and awning they can be comfy!
several small blocks of wood for leveling and helping change a flat on the trailer should the need a rise!
paper plates,paper cups and a set of silverware from the house or a yard sale.
Keep the trailer loaded just like you could hook up and leave if you had to, leave towels, clothing toothbrushes etc in and ready to go.
1 last thing is the notepad for items you forget or decide you need so you don't forget them next time your at the store.
I have a web site for RVMAts if you want to look at them.
That's all I can think of right now but I am sure there is more.
Terry