backstrap bandit
Anything can be done if you willing to do it or pay someone to do it. In Germany we had Rolladens windows covers mounted to the houses. The covers rolled up into a box that is mounted in the wall and stick out a bit above the windows.
http://rolladenlv.com/I'm sure you can make a roll up hatch with a heavy felt seal and then a rain channel to catch any water.
The Air going over the back of the TD while driving might try to bow the middle of the door if it is not stiff from side to side.
Another thing to look at is the hatch gives a little shelter while cooking

. Keeps bird poop out of the bacon and eggs.
Keep us posted