Depending on what you want to do, there are a lot of decent places to camp in Ocala. Lake Dorr campground is right on the lake and you can fish, canoe, or whatever. I would also recommend Blue Springs for family camping.
Definitely go to Alexander Springs in Ocala. The D loop is excellent and has some really nice secluded sites. I've been a few times and really enjoyed it.
in alexandria springs, when you say "Secluded" how do you mean? I like rustic camping, like out in the wilderness, my wife likes at least a bathroom. But we both hate being right next to rvs and others when we are tenting. Would this be a good area?