Since he has custom upholstered seats, it would only ad one step to your DIY, which is just taking apart back seats and installing heating element.
Speaking of the heating part, rear seat - how is it heated? Just seat bottom or both bottom and seat back?
Correct on adding one step for the custom seats. As far as the OEM ones, they are heated for your back and butt. Looks like we are going to use a resistor. Ill post up the resistor and location when we do it to help out.