1 - I've checked the saddle fit, it is an excellent fit.
2 - I've had my BO (a saddle distributor) confirm the fit.
3 - I had a third party friend (another saddle distributor) confirm the fit
4 - Lots of saddle pads tend to slip backwards on him
5 - I've tried a few different types of saddle pads and thicknesses
I ride using an English saddle. I've noticed that the saddle pad, under the back end of the saddle (under the panel), when he moves, he's so bendy that he's literally rubbing under the pad. You can hear the pad going "swish swish" very softly as he moves. I've tried this with the pads that claim to mold to the horses back and not slip, as well as a variety of regular pads and combinations thereof.
Does anyone have any suggestions as to either something I can apply to him to prevent irritation or preferably a saddle pad suggestion?