[skyking]

I get that part. It was more a search for simple and foldable construction.
Now I am having second thoughts about the boat tail. The Ac unit is not a negotiable item in my household. As you said, it trashes things up there very badly, along with the rear kitchen vent.
I look at it and see a full and properly curved rear fairing starting at the high point of the roof, cleaning everything up and ending in a Kamm back about 1 foot aft of the current roof. If I play it right, it will be heading down at way more than a paltry 12 degrees and follow your recommended form. It would have a transverse bulkhead to separate the front and back of the AC unit, with a vent above for the inlet air to the condenser. I'd seal that area up in front and utilize the proper type of inlet that will let the air pass over it smoothly.
I'd need your help designing that.
The aft side of the bulkhead would vent out along the edge of roof.
It would provide the perfect point to mount a shorter and curved boat tail.
I am working on that geothermal system so I will be a few days before I can draw anything.
I think it would clean things up considerably.