Class 4 hitch on 2010 8280WS - how much will it support?

[Enliven]

Bought a used 2010 8280WS which had what looked to me like a factory hitch installed but I now know it is not.

The hitch is welded to the frame upright and top and extends into the frame about 1.5' (back to the first outer support) and welded all over everywhere - not attached to the bumper in any way - a really good install job.

I am aware that the frame and pin box are the limiting factors and dont want to push it past what could be determined as safe.

Love to hear from anyone with experience with an Ultralight and a rear hitch, assuming Im not stoping/starting fast and keeping it under 65- what do you think the limits are for total and tongue weight for doubling?

[Enliven]

bumpity bump..

[rockfordroo]

Suggest you post pics.