Pulling 7500 pounds with a gas unit will be a challenge. You need to look both at the hitch rating and the overall weight rating of the coach and anything it pulls. That is called the GCWR. I was looking at class Cs's and found that while many had a 5000 pound hitch, they could not pull a 4500 pound vehicle because it would cause the set up to exceed the GCWR. When you look at the numbers, you will see the weight of the RV when empty but filled with fuel. Then you need to add the weight of the passengers and all you will carry - do not forget any water you may have in the tanks. Then you add what you will pull.
I think you will find that you will need to look at diesels in order to be able to pull over 5000 pounds. Look at used coaches that have been well cared for. Get maintenance records. The brands I would look at are Newmar, Country Coach, Tiffin and Winnebago.