Ain't no way you're going to do this with a small class A. A 5000 pound hitch is only good for 500 pounds of tongue weight at the bumper. 1000 lbs of motorcycle and lift that far back is going to put 1500 pounds on the rear axle and take 500 pounds off the front axle.
Reinforcing the frame is not going to help as you are over the weight limit of your rear axle. There's a reason you only see them on the back of big DPs, usually tag axle diesel pushers. Most of the CCC of a small class A is used up in the stuff you put in it so you can forget adding even 500 pounds that far back.
You might want to click on "How I Tow" below as I know a fair amount about putting a lot of weight on the back of the motorhome.