RV parks are slim pickings in that area anyway, and all along the Gulf Coast for that matter, since Mardi Gras is celebrated all along the coast. (Mardi Gras originated in Mobile!)
The casinos in Biloxi may be your next good bet, but even they will be limited. Wherever you go in that area, though, check the local news, etc. It is not uncommon to get stuck behind a small town Mardi Gras celebration or have major highways (non-Interstate) blocked for hours. Been there, done that.
Even over here in Orange Beach/Gulf Shores, our park will be maxed out, as will another park we stay in at Livingston, LA outside of Baton Rouge. It's a big deal, but then you knew that. 8)
Kim