I would agree with checking out Arcadia. Below is a link to parks in the Arcadia area. There are a few just north of Arcadia that would fit your description. One park we drove though last year that we thought was very nice was Cross Creek. Very nice park. We just recently stayed a week at Riverside RV Park which is actually much closer to Port Charlotte than Arcadia. It's a great park, but if you're budget minded it may be a bit expensive. The pools are nice and there are a lot of activities.
PS: In regard to golfing in Arcadia, we passed 2 golf courses along Hwy 17 not too far from Cross Creek.
http://rvparkreviews.com/regions/Florida/Arcadia.htmlYou might also check out Sebring. Rates are much less the further inland you will go compared to either coast. We're at Highland Hammocks State Park in Sebring right now. The weather in this area is much warmer than further north. We stayed at Whispering Pines Village for a few nights last year. It's a nice little park and while it didn't fit our needs for the future the people running the park and the residents we met were very nice. It's an active park with plenty of activities for the residents. The big plus is that the monthly rates are in the $450 range. We met a fellow yesterday in downtown Sebring (also originally from MI) who told me that if I loved golfing then Sebring was a great spot. He said the rates here are much less than the coasts. We drove by several courses and they sure look great.
http://rvparkreviews.com/regions/Florida/Sebring.html