Nature's Coast in Steinhatchee would be awesome! Unfortunately, we are not planning on heading that far east this winter :( Well, wasn't planning on it, but that is a great suggestion...
I was thinking late winter, early spring. Most of the travelers are in the southern states, so at least we can narrow down the location that far.
My requirements: somewhere warm, relatively cheap, stuff to do in the area. Water in the area is a plus. High tolerance of park owners/hosts is important - we don't need to be getting kicked out of anywhere ;)
So, February, March, April in the southern US. That should narrow it down 
--kev