I checked freecampsites.net to see if there was a place to just pull in for the night and it looks like a tough area for an overnight. I think that's what you'll have to do due to your late arrival time. Here's the note for the Walmart in Ocala
"2600 SW 19th Ave. Ocala Fla. 34471 Management allows over night parking preferably in large parking area next to garden center, however there's never enough room and RV's, campers spilled out into other areas of Walmart parking. Location is surrounded by resturants, retail stores to accomodate most every need."