A few things we have found we like/need to have:
Need - A really
good sewer hose. Not the cheap piece they give you as a starter. I forget the brand, but we have a red hose that has the ends built on. Well worth the money!
-A sewer hose support. Slunky or catepillar or whatever they are called. It only took me one time of trying to get the hose to drain by holding it up in diffent places.
-Black tank flush if you dont have one built in.
-X-chock to go between the tires if a dual axle.
Like - Oversized antigravity chairs
-Bins to organize hoses and blocks in exterior storage
Have fun discovering all the things you find you want/need.