Hi BionicBilly, If your horse is that sensitive skinned and backed, you might also want to try a thinline pad in the mix.
This would be my favorite recipe: sheepskin halfpad under saddle cloth under thinine halfpad (is only 3/8" thick) and then Fhoenix panelled version. The thinline pad is made of state of the art absorptive material that is thin but ultra absorptive distributing the shock along the pads surface laterally rather than up into saddle or down into horse. My horsey loves this combo the best!