bolt on backrest
Try the Hepco & Becker bolt-on back rest. I got mine from Accessories International. Part no. ET 700.307 fit onto my H&B Alu Standard top case and the wife loves it. Mine was $63.
They have others that fit their other alu cases. Google hepco&beckertopcasebackrest for more.
Call them at 888-725-3679 for pricing.
No, I don't get anything out of this referral. They gave great service and the best price both times I have ordered from them.