H'mmm.... the plot thickens..
Wish I was there in person to inspect better but here goes. You see if this fits with what you are seeing.
I did not see your final setup, so I'm going by these 2 pics which I "think" you came back to. Did you?


OK I'm going to break down each of your comments to see if I can add this all up. I added the blue numbers
mrekim wrote:
Simple round trip to the dealer and the snap up bracket bent.
1. There's a bend in frame where the pinch bolt for the snap up goes
2. as well as 2 smaller bends where the snap up ends on the outside
3. and 2 small bends at the top of the dual cam.
Everything was tight - and not too tight - before I left.
Here's the snap up:

What a mess.
Here goes..
No 1. The set screw frame bend, I "think" this bend happened 2nd, not 1st.
No 2. 2 smaller bends in the A frame wall at the ends of the snap up. This "might" have happened 1st.
No. 3 2 small bends at the top of the DC frame plate. OK which way is the bend? If the A frame rail bowed in or bowed out? It could be either way and you did not state. This answer really helps tell a good part of the story.
The snap up keeper clip bent last after the frame and snap-up caved.
OK see this turn, did you turn real hard left in the truck?
This is 74 degrees left, this is OK

This is beyond 74 degrees left. About 76 ish. This is not good.


Here is the same setup, (TT & TV) straight ahead

Now lets look at the snap up toggle concept.
Here the snap is over center and the keeper clip locked. The chain hang (vertical line the chain makes) is in line with the snap up pivot pin.

Now the snap up is not clipped in place and slightly open. The chain hang is now outside the snap up pivot pin.

OK how does this all connect? I really need to know on no. 3 if the DC bent into the frame or pull out as the forces of that event sort of tie all this together.
Before I speculate, let me know this.
Thanks
John
PS, your frame fix with the plates, yes this is a good thought. Make sure the 6" wide plate fully reaches the to top and bottom of the A frame rail so the compression is backed up by the top and bottom leg of the tube frame. You will have to fine tweak the anti crush tubes to get just the right squeeze.
Also any idea of the thickness of the A Frame tube? Ideally with a caliper but I'll take what you to can get. This tube crushed way too easy. They keep thinning these things up. I'll stick with my heavy 6" channel iron.
BTW, Rees may replace the snap up under warranty, they have a lifetime warranty.