That looks like a tough one :-)
But since you asked, and opinions are free:
1) Use a non motorized Xenarc !DT 700 ? If you mount it where the single din opening is conventionaly (upright), its gonna block the two center AC vents. This may or may not be a bad thing as the current "high brightness" one that I have does get pretty hot on hot days.
The benefit being that you avoid all the "motorized" hassels. Its manual, works well and isnt gonna break under normal use.
Im not sure if ther is a way to mount one upside down and flip the video image, but if there was you would be good to go.
2) Delete the two center AC vents ? The bottom outermost left and right corner of the two vent openings (in other words the area that would be inside a rectangle drawn around both vents) appears to be about the right size and location for a screen. It appears that that entire bezel that the vents are in is one piece. You could square off the opening to fit a 7" screen and cut back and reroute the AC going to those vents with flexible tubing redirecting it to come out elsewhere. You could add a vent that would blow directly at you, or just redirect them to blow down and come out from under the dash. Yes, not as effective as they are now, but they still would work. And the work required to fit a rectangular screen in that space wouldnt involve much (if any) contour fabbing, you might be able to trim it to the point that required not additional work.
3) Move the heat/ac controls either
Down, might be able to fit the unit as is into the dash just below where it sits now by trimming the sides of the opening.
or
Up, would require you pulling the actuators off the original unit and mounting them in a smaller faceplate that would fit in the single din opening. You would have to do new lables for the faceplate transferring any info off the original plate to maintain the same functionality.
Just an idea.
I wanted to keep the factory head unit in my car and the space directly below (where I would like the screen to be) already contained the heat/ac controls.
I wound up moving the heat/ac controls down and used the 700 IDT.
Worked for me, Im happy with the set up.
Well, photobucket is being tempermental

I was gonna post what I did. Ill check tomorrow and see if it is available and post a shot.
Good luck with your install