I flipped over the horizontal stabilizer and used some ratchet straps to start pulling it tight. I only had 4, and there was a little too much bending around each of them for my comfort, so I pulled them off and put a long 2x4 under it to distribute the pressure. Unfortunately now it was really difficult to apply lateral pressure to pull the skin into place, and it was wanting to press down more than anything.

To get a more even pull we ended up walking over to Walmart to buy a pack of 4 more ratchet straps.

With those in place I got it lined up, drilled #40 holes, removed the straps, and widened them all.

I started cutting the rear bracket but it takes an extraordinary amount of force, so I gave it a rest for now.

Update:

I came back to the rear bracket late tonight and spent a lot of time snipping and filing, and it should be good now.