You haven't traveled the Ohio Turnpike.
The recently renovated service plaza's on the OH turnpike have a separate area for RV's that includes at least 30A service. They are relatively inexpensive, no attendant, you just pay at a kiosk (have to put your receipt on your dash so a patrolling officer can see it if/when they come by). The only real downside is that many of the plaza's only offer back in sites--thus if you've got a toad you either disconnect it or just park by the trucks.
Easy to back in with a 5er:
Not so easy with a toad:
I'm pretty sure its the same service plaza on both pics (just separated by 3-4 years). With the Axis we're on the truck side; the RV spots are away from the trucks.
LOL! Of course in this
Google streetview you see a motorhome with toad that found a way.
Having said all of the above: I'd love it if more states provided such small overnight spots like this. We would use them quite a bit.