My wife is thinking that she needs the passenger pegs to move forward some so she can more easily have her foot on the pegs when riding with the bags installed. These are probably the answer to this, thanks for bringing it up Stewart! Looks like the rear bracket part number is 051 05 03 10 for the passenger (051 05 03 00 for the rider) for the C14 (pegs and extenders are separate).
Extensions:
Extension for Vario Mounting Bracket, 23mm 051 00 00 23
Extension for Vario Mounting Bracket, 30mm 051 00 00 30
Extension for Vario Mounting Bracket, 50mm 051 00 00 50
I guess it can get expensive with having the 3 different parts all separate...