I finally came around and installed this tail tidy from Evotech. For a while I was uncertain if I should go this way or make a LED-strip arrangement from Radiantz or similar, but chose this since it is CE-approved and street legal.
The turn signals are also Evotech, and I ordered the 6-pin Deutsch connector that corresponds to the stock connector under the exhaust, so the stock harness is still complete and untouched.
The Evotech tail tidy is a bit pricey, but very high quality! With turn signals and number plate light I paid about 250 Euro (325$).
Here are some pictures, taken by mobile phone so not very good I'm afraid.