1. He wears a martingale and I've been told to tie the martingale to the saddle and it will hold it is place. Will this work? I'm not very sure about it.
2. A breastplate to hold the saddle correctly. Would you be able to use a breastplate with a horse that has a martingale?

This photo it was in an ok spot but usually it slips even further back. I had to get off him yesterday because the blue pad was touchin his flank and he was getting upset about it. And I do put the saddle up high onn the wither and tighten the girth. It just always slips back