Now here's what I did...
I didn't really have any intention of messing with him, but since I had him taken apart, I figured I would see what I could do with some hot water...
If you choose to try this,
proceed at your own risk! I heated up some water in the microwave just shy of boiling, about 3 minutes on high, pretty hot but not boiling. Dipped just the bottom of the vest in for about 20 sec or so and bent the bottom plate to my liking. Here's the thing though, the clear plastic backing acted almost like a shrinky dink and kind of got a little warped as you can see below. Not really a big deal to me, it's hidden and still functional but, once again,
proceed at you own risk If the water had been hotter, or I left it in longer, this may have proven disastorous!
Anyway, with some curvature in the ab plate, I decided to put him all back together after letting things cool and dry and this is the result:
Since I had the water out, I went ahead and water treated the Wookiee scalps as well. They are still wet in these pics:
And here he is, all put back together: