Right side of car.  I'm holding up the rearmost rubber air dam.  Above that is a dark grey piece (circled in red) which is part of the inner wheelwell and also goes under the car to the right of my hand.  This plastic piece gets really beat up and is really a design oversight in my opinion.  Something this low and exposed should either be flexible to absorb minor impacts, or strong enough to absorb them. My friend who is a Porsche tech told me that it's not uncommon for them to replace these.  Above this grey piece is a black piece of metal that supports the radiator (yellow).  Besides installing a screen to keep stuff from going up into this hole, I intend on protecting this piece from minor impacts in some fashion that if something really hard hit it it would bend or break away instead of causing more damage to the radiator frame.

Mock up of screen.  The pointy end would be at the front of the car.  The rear (bottom of the photo) still needs to have a piece of aluminum attached.  The screen will be epoxied to the aluminum frame. Att the parts you see here was bought at OSH, with the exception of the Marine Tex Epoxy which I have from an old boat project.

Left side, with aluminum pieces installed, rearmost rubber air dam reinstalled, forward air dam hanging by aft mount. If you go up to the first photo you can see this covers up the exposed plastic fender liner piece that tends to break rather easily.  It'll also serve as a mounting point for the rear of the screen.  Threaded fasteners clips things (not sure what they are really called) are installed, but holes not drilled yet, mocked up to which the screen is to be mounted.

Right side being mocked up:

Right side done and readu to be installed/  The large holes on the top (actually the bottom when installed) are so that a screwdriver can be inserted to bolt it to the car.

Modifying the right side rubber pieces:

Mocked up and ready to install:

Backside detail:

Final Installation:

Painted, rear flap not reinstalled yet.  I may not reinstall these pieces as they do not have any noticable effect on temps in daily driving, but they do get beat up pretty good.  I'd imagine at high speeds they manage airflow, but we don't have the autobahn in the US.

Cracked undertray.  This is the tray that is located in the front of the car.  Pictured is the right corner in the front. A brake air duct, which hangs off the lower control arm and channels air to the brakes, can be seen to the right.

Cracked undertray fixed with Marine Tex epoxy.  This is a pretty vunerable area and I am surprised it wasn't made with thicker plastic, or reinforced with webbing to prevent this from happening:

Undertray reinstalled:

Detail.