The BOSS is a good addition as well as an all-around sound diet and moderate grooming.
My horses seem to benefit greatly from having the vac n blow used on them (usually blowing) to get rid of the scurf and grit near their skin. Nothing else does the job as fast or as easily.
I live in a very wet environment and for lots of reasons, it causes skin problems, but I think blowing away the coat helps a lot as well as grooming them once a week, at least! (Don't wince, Marty, it's the best I can do when it's just me, here!)
If you feed a good, nutritionally balanced feed, and keep 'em groomed, I think you've got a good start. The other things will help some, for sure, though.
I've noticed that my show horses that get BOSS, when I clip them and then go to bathe them, the water beads up on their coats like a car after it's been waxed and they tend to have a thick, almost greasy quality to the skin especially if they have not been bathed in a while.
Liz M.