This is where Tailwind is today. It is used on recumbents. It used to be a 4 bag set for touring bikes.

http://www.angletechcycles.com/asset...s/techwind.htm

There are some solid options that are pretty aero, though most of them are also aero from behind, which is a mixed blessing.

Trailers are often quite heavy, heavier than most racks, and they have unique rolling resistance issues, and braking issues. A good product but not better than racks on all fronts.