Our total length when towing is 46 feet. We are not as tall as you but have 3 slides. Don't give up calling the parks. I have called many parks before making a reservation to get a recommendation for a campsite that we could get to with our rig and that we fit in. I have found the people I've talked to very helpful.
I always look at a map of the campground and read a description of the site if available. I also try to get a pull through if possible.
We just returned from a 3 week trip and stayed in a TVA park, 4 state parks, and 3 COE parks.
Good luck!
