No. There is not even a website or directory listing all campgrounds in the U.S. Based on the number of campgrounds and small RV parks I pass traveling the "back roads" through the middle of the country, I suspect the best listings might include half of the RV parks, and fewer than a quarter of the campgrounds.
Most listings have "minimum service" criteria that tend to exclude small public campgrounds in out of the way places, and "convenience" RV parking at gas stations, small motels and travel centers. Listings are starting to cover RV parking at casinos, but not the camping networks at farms and vineyards. RV parks that primarily serve seasonal workers mixed with permanent residents, and RV parking in mobile home communities are also usually excluded.
Most of these places that are not in listings will not have reservations systems, so you would not find them by availability date even if they were listed.
For campground systems like the recreational access facilities at Corps of Engineers Lakes that show up on the recreation.gov reservation site, all that will be listed will be what is reservable, while there are often additional campsites (and whole campgrounds) at the same Corps project that do not get listed because sites cannot be reserved.
If you are looking for a certain class of RV park or RV-specific campsites in campgrounds, the best starting point I've found is RV Park Reviews, though it does not provide reservations service. What it does well is help to identify the types of campgrounds and RV parks catering to recreational RVers.
Tom Test
Itasca Spirit 29B
