As I have mentioned in other threads, engine bay cooling requires you to get cool air in from outside and provide a place for the hot air to vent out so you have constant air flow thru the engine bay to keep the temps down. This aids in longevity of the parts in the engine bay...like your transaxle. I recently made the Side Scoop Louvers available here to help get some fresh air into the engine bay. The only way those Side Scoop Louvers can get fresh air in is if there is a place for the existing air in the engine bay to get out. Otherwise, the Side Scoop Louvers are just trying to pressurize the engine bay and you get no flow. These parts would give all of that air a place to escape. Here is a CAD drawing of a couple parts I could offer to you guys.
The top piece would be for the area between the tail lights. This one would be for the AJW exhaust with a single 3" outlet. The diameter of the hole is 4.25" to provide 5/8" clearance all the way around the 3" exhaust pipe. I could also make this panel without the exhaust trim hole for those of you not using that exhaust. I could also incorporate the license plate mounting holes into this part for those of you planning on mounting your license plate in this area. This piece would bond to the inside of the body....the outer "flange" would not be seen. The hole in the body would be cut undersized so the flange would be hidden behind the body.
The lower piece would be for the area directly below that. This piece is set up for mounting the license plate with vent holes on both sides. This part is designed to mount to the outside of the body where the flange around outer perimeter would be visible. This could be bonded, bolted or riveted to the body. As with the top piece, the license plate mount could be eliminated and the whole area could be vented.