Here's an update for you all:
I had to call several places yesterday morning, but found a shop that was willing to work with me on such a short time frame. The benefit of this place is they are close by and happen to specialize in RV collision repair, so I'm guessing they're going to make sure they do the job right.
They didn't want the liability of simply patching it up and risking it coming apart on the road and causing a major accident, so they are going to completely rebuild the A-frame with thicker wall tubing. It is not going to be cheap by any means, but it sounds pretty involved, as they said they are going to have to unbolt and lift the box from the frame about a 1/2" in the front so they have enough clearance to weld without catching anything on fire. They said they'd have it done by Friday, will give everything a nice paint job, and it should look like it's never been touched. Another benefit is the thicker wall tubing should mean I'll never have to worry about the tongue again.
To think this all started simply because I was going to respray the front of the frame to cover up the rock chips. Talk about an expensive paint job! I still feel lucky that I caught it, as I can't imagine the potential disaster had that side of the A-frame completely torn apart at 65 mph on the freeway.