The Drifter has a unique rear setup, and so you can't mount a rear rack on it in the same way you would other bikes.

Does anyone know of any other racks for a Drifter 1500 besides the Kawasaki Fire & Steel, the Wompus rack, or the Scootworks racks?

I'd like to mount a trunk/backrest from time to time, but the racks mentioned above cost more then the trunk. That seems kinda insane to me.