Must have RV accessories

I picked up all the must-use-daily things and store them in the camper....mostly items that are easily overlooked and forgotten...like toothbrushes, toothpaste, contact solution and case, pillows, etc.
I'll second the TP, but point out the RV kind breaks down better as it is made for camping and won't clog drains...I have heard that certain brands are ok if you use lots of water, but dealing with clogs in the camper doesn't sound fun...I'd rather pay a bit extra (Walmart carries it for about $2.50 for 4 roles).
I'd advise you take your first trip to a place either close to home or close to a Walmart or other convenient store..load up what you think you need and get what was forgotten.

We bought The Swiffer Sweeper Vac based upon a recommendation from my Aunt who has an RV and I love it!

Other things I'd add:
A bin for the shoes outside the door
Fuses
Extra Batteries
A Binder For All Your Manuals (already had to bust them out!)

My Additions to the List:

Bottle Jack large enough to raise your trailer. ( 10,000 #)

Spare lug wrench

Electrical adapters for your electric cable.

collapsible water jug.

If you have room, one of those square tents for over the picnic table.
(Not a must)

Extra pieces of wood or plastic spacers for under your stabilizers and Hitch stand. (Minimum of 10)....a must!

You know of course, this will never stop. LOL

Dry erase board. We have alot of gadgets in the rv. But we would have forgotten most of them if it wasnt for the board we write on whenever we need or forget something

Portable ice maker! Don't leave home without it.

Water Thief.

Flush King.

MasterCard or AMEX
Everything else is easy

A really good flashlight.

Tools, definitely!

What we did our first night out last month was think about a day in our lives from start to finish. Wake up, then coffee. So a coffee pot, coffee and filters. Then we realized although we prefer regular coffee over instant, instant is better. Doesn't require a pot either. Then a shower. And so on.

A good mattress topper.