My rear rack obscures my seat. I don't even HAVE a reflector mounted on my seat; I took it off. It's useless, and it was in the way (I now have a suspension that takes up that space).
So I could mount tail lights there, but again: useless. You cannot see them from behind. Complete waste of time and money.
Where do I find tail lights that mount to a rear rack? I don't want panniers, rack top panniers, or baskets to obscure my tail lights. Tail lights belong on the back of the bike, not somewhere in the middle with a bunch of crap in the way.
Also prefer something bright, and LED based. I might try to rewire various things (headlight, tail light) for bike dynamo.