Definitely get the Bal X-Chocks. They are awesome!
A good sewer hose was already mentioned. I can attest to that. Inspect your hose before using it to make sure there are not cracks or punctures in it.
Popup Gizmos was mentioned to. THESE ARE A MUST!!! It is amazing how cool our trailer stays even in the middle of the sun because of the Gizmos.
Water hose, with pressure regulator to protect your internal plumbing from pressure spikes. I also got a "L" coupler so the water hose doesnt have to bend to make the connection to the trailer.
A ladder of some sort. I take along a collapsable 6' ladder with me. It helps me to put the Popup Gizmos on the bunk ends, and to sweep off the top of our slide out before leaving the campground.
