I would highly recommend replacing the stock Ford shocks. They were grossly inadequate on my 24' E450 class C (when new) which is well below max weight rating. They did not have enough control. I used the Koni FSD and can recommend. I also think the Bilstein HD would be fine.
I think there is lot of confusion here about the terms ride and handling. What I'm addressing with this post is the excessively loose control of the suspension with the stock Ford shocks on the class C motorhome. The Konis, at least, firmed that up without making the RV harsher in ride quality (slam, impact).