Parking a Truck Camper at a Tent Only space in Yellowstone

In my experience "tent only" at Reserve America and elsewhere means no hookups, exactly what I want with my TC. Look at the maximum vehicle length to make sure you fit.
To those who say that only means only, I ask: What site do I use if arrive in a in a passenger vehicle and wish to unroll a sleeping bag on the ground, both tent-less and RV-less?