We love Riverside RV Resort & Campground located between Arcadia and Port Charlotte - going back in January for the 3rd year. It is located on the Peace River (boat ramp at the campground), which is part salt near the Gulf and fresh the further you go upriver. Friendly people, lots of activities, convenient but quiet location. The longer you stay, the cheaper the monthly rate. There are 3 different areas, with the rates varying depending on the area and how long you're staying. We stay in the "Premium" sites (middle level) for 3 months and this year's rate is $1,169 mo., 30 amp. serv. inc./extra $45 mo for 50 amp.). The Lakes opened last season and is the top tier with huge sites. Being newer, this area is probably your best bet for getting a site this late. Monthly rate for a 5 month stay is $1110 ($1268 for 3 mo.)
The fact that so many folks return year after year says a lot about the campground. Check out their website!