Just remember (depending on what year Gold Wing you have), if you replace the backrest, and it's not heated, you will lose ALL the heating elements in the entire system!
Riders Heated Handgrips.
Riders and Passengers heated seats.
Actually, replacing the passenger backrest with a non heated one has no affect on the heated seats and grips. I have an aftermarket passenger backrest on my 2012 and the heated seat and grips work fine. I had the same results with my 09,07, and 06 Goldwings.