I've got a 97 R11R, and I'd feel safer with the wifey back there dozing if a sudden acceleration didn't risk spitting her out the back like a watermelon seed. Seems Reynolds racks are no longer made, though sometimes available in the Flea Market. And hard trunks are a fitment issue.
Anyone tried a Sargent backrest like this?
Seems like a backrest and rack at a reasonable price from a reputable vendor...
if you have the bmw rear rack, there is a passenger seat adapter that slides right in. You can use it with the stock (or other) saddle. Got mine off of eBay for cheap.
Rock 'n roll!
You could try Pirates Lair - http://piratesk12site.net/
I have their backrest for my R1150R and it is awesome! I don't see the R11R listed but you could check with them.