Check my photos. I have a TBA and had a homemade driver's backrest. Construction details shown in photo. Need 1 L-bracket from a hardware store, aluminum, 1/4 inch thick, for the upright, and a straight flat bracket for the crosspiece to mount a pad. Hid the crosspiece by mounting a vynal-fabric pipe tobacco pouch with a zipper.
My cost was $60 for a custom made leather covered pad. Very comfortable. I took it off after a few years to allow for more passenger room for my teenage son. I still have it in the garage, for long trips-takes about 10 minutes to install it again.
--Tom
