We have not camped at Anastasia but have driven thru a couple times.
Sites tend to be slightly cramped but I think you're "little" motor home
would fit many of them.
I just for fun checked the FL camping site-
Welcome to Florida State Parks
And punched in a range of dates in May at the reserveamerica website.
You can get in Anastasia but you will have to move a time or two as
site open dates are all over the map with 2 to 5 days open on different ones.
Depending on when and how long you want to stay it looks doable at
present time but sites are filling up fast!
Good luck in your trip!
If you do make reservations at Anastasia drop a line here just because