I suspected that my "new-to-me" Wildcat had a similar issue after noticing what appeared to be some flex while under tow. I couldn't say for sure if the flex was in the pin box, hitch, or frame...so being bothered by it, I decided to tear out the fiberglass cover and inspect for myself. What I found is that there were no cracks or breaks, and the structure appears fine. The fiberglass cover did not go back in the same way it came out.
If I were you, I'd do the following:
Rip out the cover.
Call a mobile welder and tell him to bring a few misc. pieces of stock bars/angles/channels/etc.
Have the welder fix it up...less than a day, and maybe less than half a day. (We're paying anywhere between $75 to $90 per hour for a mobile welder). Make sure he grinds off the original welds and paint.
Go to hardware store and buy some primer to paint over the new welds.
Re-install cover.
In my case, like I said, the cover didn't go back in the same way it came out. I actually cut it in half and installed a new backer board. In the near future (after my labor day camping trip), I'm going to have one of our local fab shops get me a 2-piece aluminum diamond plate cover to replace it with. I've already been quoted $375 for this.
The whole thing should not cost you over $1000 to $1500.