Those are all good suggestions (handlebar/riser/backrest/peg relocation) posted by others here. A backrest fitted Corbin seat made my longer rides very comfortable.
I am guessing from your ND location, you bought from Bob at Ma's Cycles. I've stopped in there a number of times as they are along my regular travel path. They might have some additional retrofit ideas, or more to your original question, a demo Bonneville sitting on the floor
jh
