If you rent the RV, you'll also need to get sheats, blankets, toilet paper, cooking utinsils, pots and pans, dishes, lawn furniture, and anything else you want. These things will not come with the camper rental. Places like Cruise America will have rental packages for outfitting the camper with the pots and pans and dishes and silverware and such, but it cost a small fortune too. This is something you need to consider and understand before renting the unit and expecting it to be fully equipped like a motel.
Also, June and July, anywhere East of the Mississippi River, you'll need reservations, private parks and State Federal or you won't get in. June-July is absolute prime camping season, and everything, and I mean EVERYTHING gets booked months in advance. So do your reservation as early as possible.
If you go West of the Mississippi river, you'll have much better success at non-reservation camping because there are much more opportunities for boomdocking than there are East of the Mississippi river.