Just a short update to close this topic unless someone else has something to add.
I consulted with a professional hitch guy at a major dealership and he advised that he could easily install a class 4 on the coach that would support much more than my anticipated weight. He could NOT guarantee the coach suspension could handle my weight...but Ford has already told me it can. He did suggest I add air bags to the rear to level things out and improve any steering degradation might occur.
My calculation is that the addition of my actual load and carrier will result in about 1000 lbs extra on the rear axle weight... or about 300 lbs more that the class 3 hitch would have put on it. I think I will be well under the GAWR rear of the coach... so this looks do-able.
I'll know for sure when I write the check and get under the coach to see for myself.. but I have a fallback position of using the Swivelwheel system if it doesn't all work out and stick with the factory hitch and a 300lb tongue weight.
Thanks to all who chimed in to help.