I just got back from an awesome 5 day trip on my 09 Sportster XL1200C. I had a bag on the passenger seat and really appreciated the support it gave my back. I went for a ride today without the bag on the back and started thinking that I should get some sort of driver's backrest. I have a sundowner seat that I had customized with gel and memory foam and it is quite comfortable. I am looking for advice on a good driver's backrest that I can add to this seat.