Some places you can use a tent site - but you have to ask. Some will have a communal power and water hook up that may be you can hook up just for a while and fill your tank and charge batteries.
The Corps of Engineers system has small RV parks at some facilities like locks and dams. There are several in Florida I know of and they are pretty reasonably priced. Another option is municipal parks in small towns.
If you were ambitious, you could collect a listing of such places and make a website for sharing the info. I agree with you though, that there will be alot of demand in the future for lower-priced, non-destination type RV parks. It seems to me that prices have really spiked up in the last few years, yet the parks have not really been improved any.
