1998 F53 extended chassis

[Solask]

1998 Winnebago Chieftain 33w...F53 extended chassis.
Talked to Winnebago today to discuss 3500lb hitch rating....I was told that the welded extended frame of this chassis was a contributing factor and they could not recommend upgrading to a class/type III hitch to increase rating to 5000lbs. What a disappointment!
My next step is to ask the trailer shop I've been talking with if they could "beef" up the welded extension area to safely improve this. The frame width of 28" will accept the type III hitch but if the extension is the issue???
Does anyone have any experience with this kind of situation?

[Gary RVRoamer]

I've heard of a few people beefing up the frame extension to handle a heavier duty hitch, but never heard any long term reports on the success of it. Most welding shops won't want to touch the job for liability reasons, but maybe you can find some big shop that has insurance for that sort of thing. For sure you can find a shade tree welder who will do it, but you will never know if his mods are good, safe engineering or just good-looking pieces of extra metal. Shop carefully!