I'm a native Floridian and stay in campgrounds for camping for a week at the most, so I do not know many 'snowbird' campgrounds, but I can give my opinion of 2 areas to look in your search, that I like from riding my motorcycle through the areas. The 2 areas are inland and should be cheaper than coastal Florida camping/snowbirding.
Salt Springs Resort is a nice place to stay but is NOT close to ANYTHING! They have a small store on premises but no bar that I remember. Right in the middle of the Ocala National Forrest. There is a nice place called Cactus Jacks not too far from the resort. Real forrest community bar (read country/redneck/whatever) that is a bit of a hole in the wall, but friendly.
My favorite is Lake County - it is BEAUTIFUL! Should be several that meet your criteria there. Lake County is in the middle of the state but just west and north of Orlando. Several larger communities there and some are retirement type, like Lady Lake. Lake County starts in the southern half of the Ocala National Forrest and has a few small communities in and just south of the forrest. Larger communities around Leesburg and Tavares with lots of shopping and social watering holes.
I stay in a 'snowbird' campground for 'over 55' during Leesburg Bike Fest during April. They make exception during the bike festival for some of us from North Florida since most of the birds have flown north already.
Just from memory, riding down CR 473 I saw an RV park, but I do not know their rates or availability but were within bicycle range of shopping/watering holes. I stay in Haines Creek RV, farther north on on CR 44, at the end of CR 473, not quite bicycle range of grocery stores but a few watering holes with grills for lunch and dinner. CR 44 can be a bit busy for a bicycle but CR 473 had sidewalks and less busy. Shopping to the south - on 441.
Ocala (the town) is on the west side of the National Forrest on 301 should also have plenty of campgrounds that meet your criteria too.
I personally do not care for the Orlando area and I-4 because of traffic. But get away from there, and there are several areas just off I-4 that snowbirds and retirees flock to. I have friends in the Lakeland, Bartow, Winterhaven, Haines City area, and it grows in population during the season of the snowbird. Sure you can find something around there too.
Bob and sometimes - Nina - a Staffordshire Terrier/a SPOILED pit and her kitty Spaz
2006 Dodge SLT 2500 4x4 Cummins Quad Cab w/AT and 3.73
2007 Salem Sport LE 26FBSRV (TH) w/ my Victory Motorcycle in it or a EZ GO Shuttle cart.