Confirm with the MH manufacturer that the Ford and the hitch manufactures specs have been maintained. Also the use of weight distribution hitches.
Due to the frame extensions on our 06 E450 Outlook, The tow ratings remains the same at 5000lbs, but the tongue weight is reduced to 350lbs from the original 500 (Ford and hitch mfg). Winnebago have also issued memos advised against the use of weight distribution hitches and surge brake systems due to the added stress put on the frame extensions.
Hopefully the newer MH and manufacturers have built the frame extensions (if used) to maintain the original specs.
Ken