Funny that you mention hidden Plexiglas grille blocks behind the grill cause I have been running one for over 6 months.
It needs a lot of work, my measurements were off so it doesn't completely block the lower grill, there is a sizable crack in it that has been getting worse and I'm afraid will break it in two soon. Also I used my air compressor to blow at it to see how it would work at highway speeds and even with a piece of aluminum bar to support it the Plexiglas still flexes and lets air in on all sides.
Was good for a first go though and it proved to myself that the car would not get anywhere close to overheating.
Here are some picks.
You can just make out the crack in the middle of the pic below and if it wasn't for the glare you could see that the Plexiglas stops about 1/3 of an inch before the top of the grill.
I'm working on an external one and have gone through 3 prototypes but the one I just did is just the right size so when I find a good building material I already have the size and shape all worked out.
I'm actually been on the lookout for a discarded car bumper. Being rural NC people get into car accidents and just leave whatever broke off on the side of the road.
Once I get one and cut it to the right size a friend of mine paints cars and will hopefully have the time to color match it so the wife won't have any objections.
Though I am open to other free/cheap all weather paintable materials if anyone has any ideas.
I also did a cardboard mockup of an upper grill block since over 1/2 of the upper grill isn't even in front of the radiator though something tells me that would be too noticable for my wife's tastes.
