Yesterday I finally installed a seat heater kit similar to this one https://www.ebay.com/itm/Universal-M...FUnDgh&vxp=mtr
Today I tested it in 29℉ and it worked really good. Here are pics of the two switches front and rear and a pic of the front heating element being installed under the front seat cover.
2002 GL 1800
BMW 1999 K1200LT - totaled
various other bikes before
Vieux motard que jamais