What you are looking for is pretty common in eastern Oklahoma.
The Strayhorn Landing COE access area on Tenkiller Ferry Lake in Oklahoma has a concessionaire-operated marina. There are commercial operations as well, like Barnacle Bill's, combining RV resort with marina. Similarly Pelican Point Marina on Fort Gibson Lake, and I'm sure there are others I've not yet visited.
Several of the RV resorts on Grand Lake of the Cherokees have their own docks; there may or may not be a dock fee. Some have marina services like fuel. In any case, there are commercial marinas on this lake (in Grove particularly) that are not be too far from the public campgrounds at the two state parks or the RV resorts not operating marinas.
Many of the larger inland lakes in northern part of the Michigan Lower Peninsula, northwest corner particularly, have marina operations close to campgrounds or RV parks; most of these are commercial.
Closer to home for you, you'll find marina operations combined with resorts on Lake of the Ozarks (south of Jefferson City) and Mark Twain Lake (just west of Hannibal).
I've also found campgrounds with docks or marinas at the northern end of Land Between the Lakes.
I also find RV parking lots as part of marina operations all along the Mississippi River. The one I pass most often is across the river from Louisana, Missouri on the Illinois side of the US-54 bridge, I think it is called Two Rivers.
Tom Test
Itasca Spirit 29B
