There are 2 luggage racks - one takes the place of the pillion seat - which won't work for you - and the other one requires the additional side brackets (that fit over the rear fender brackets) and the sissybar. It hangs out the rear over the license plate bracket.
You could install everything but the sissybar, but that would look kinda dumb, IMHO.
Sounds to me like you're talking a custom fabrication here...
