Randy my friend there aer many campground memberships. They were a lot better years back kinda like everything else. I like the happy camper club and they offer 50% off rates. You will have do your own homework to find spots that are larger for the big rvs. One other you might check out is passport america.
Passport America is great for overnight or couple days at 50% off. We've also found a few places that extend the 1/2 off discount for a week or more when we asked. Kind of depends how busy they were. Stayed in Moab for 2 weeks at 1/2 off the week before Jeep Safari in March this spring.
We also joined Thousand Trails Southwest & Northwest zones. But only stayed at the one in Cottonwood so far. OK but we were just looking for a way to lessen our expenses. Probably will renew it later this year since we plan to travel through California, Oregon, and Washington. But a lot of these places are more family oriented and I imagine would be pretty noisy with lots of kids during the summers and weekends.
It really depends on how you plan to travel. Since you are now fulltiming you may find it better to look for monthly rentals in an area you like and want to explore more.
That is our plans when we start fulltiming (hopefully soon if the house sells).
If you're ex-military or Elks membership or others then you might find other options there.
Another option is to join Escapees club and have their campgrounds and discounts. http://www.escapees.com/
I've stayed in their Hondo, TX campground and it was nice. Mostly retirees and fulltimers. And inexpensive at $15/night + electricity.