You can do window tint, but the stuff you want is Gila Glare Control Window Film (Smoke color). You can get a large roll of it at Home Depot or Lowes for less than $20. (I'm still livin off the roll I bought a couple years ago). The part number is CS78 and it comes in an orange box. It's actually considered static film, but I've had no issue with this stuff sticking to taillights (and even headlights) through rainstorms, car washes, etc. You CAN peel it off when you want to, but it's not going to just fall off itself.
This stuff is thicker than stardard window tint, therefore it's a bit easier to work with. Make a template out of paper, then trace that onto the backing on the tint. Cut it out, and apply to a clean and wet (with soapy water) taillight. Use a towel to help work out any bubbles (not much of an issue on the taillights, especially the inner 2 pieces), then just let it sit for a couple of hours to dry.
Oh, another tip - when creating the templates, you just need to make the three pieces for one side, then flip em over for the other side.
See my latest tint work in the attached pics.
Where did you get those Mustang letter inserts for your rear bumper if you don't mind me asking?
I pulled a half day at work - went to Lowes and bought the Gila Glare tint. Did my headlights in about 30 minutes total using 1 piece. Didn't use two pieces. For the guy that tried to use 2 pieces - try using just one and follow the curvature of the bottom of the headlight. Then trace around the bottom of the headlight with a razor blade. After that, start trimming the sides. The top is the last part to be trimmed. It will crinkle/overlap in 1 area towards bend /angle at the top of the headlight. At this area, use a razor to cut a "V" section out of the top to eliminate the crinkle/fold thingy. The best way to do this is to pinch the fold so it sticks straight up, then razor it from the surface of the headlight. This will leave virtually no seam if done correctly. I bought the "Gila Tint Install Kit" - they had it at O'Reillys here in town. Hopefully this stuff doesn't peel. It is pretty thin and would be potentially easy to remove - they also sell a spray to help with removal. I will do the taillights tomorrow - same strategy of using a single piece per light and using the razor to cut overlapping/creasing areas. I will put up pics tomorrow.