This can be used with the luggage rack. The bag is 11 x 17 and 12.5 deep, holds as much as both saddle bags. You can also take it off and plug in a hitch ball for a trailer. Tom even made it with plug and play light connector, so you don't have to try and figure out where they go.
Did you notice the LED light across the back?
Interesting, do you have any more pics showing where the tow hitch connects? My towhitch has the ball just above the bottom of the fender which to me is ideal height.
Yes I noticed the LED across the back.
... you wouldn't want to put too much weight in that bag hanging that far back, it'd upset the balance of the bike... good for wheelstanding at lights I guess