You're right, nobody makes them (I base that on looking for over a year). Best bet is a set of McKesh tow mirrors or the Eagle Vision mirrors offered by Camping World.
Definitely not the most stylish accessories in the world, but when I'm towing my travel trailer I'd rather be safe than stylish.
The first tow mirrors I tried were the el cheapo clip on kind from Wal-Mart. They vibrate like crazy and the rubber straps became weathered and cracked after 1 year of light use (they were stored out of the weather 99% of the time).
