TTH, that is freaking awesome!
The tops on our blinds are held on by cheap u-bolts and the outside is covered by a heavy duty tarp held on by zip ties. We had several that we never got around to putting tops on and they worked just fine as long as it wasn't raining.
Hunter 257W, a 2x6 run crossways thru the panel just behind and below the front window opening makes for a pretty good rear rest for those long shots.