It's not what you want but I raised my backrest up 4 inches by only using the bottom 2 screws to hold it in. I did it for my wife's comfort but did change the look. It's free, try it and see if it works for you. Don't know if the Harley one will fit.
2001 Vstar 1100 Classic (sold), Cobra Slash Cut full exhaust, Dropped 1 inch with lowering links, ORK, 4.5 inch handlebar risers, Ultimate passenger seat, Passenger pegs moved forward 4 inches, Handlebar clock, KN air filter, Viking saddlebags, Additional rear lighting
Loose nut "me" behind the bars
2006 Harley Electra Glide Ultra Classic