I had a similar problem with my horse.....after about a
year of riding he started developing the shedding of skin post 50s. I covered
the girth with fleece (and keep it clean) and stopped that problem. Now, another
year later, and the galling right behind the elbow started. Solved that with
using the center fire position on my Big Horn. Now, no problems at all.
I do use a crupper and it was no problem getting the
horse accustomed to it. Just put it on loosely, lounged to see if it caused any
problem. Then tightened up until snug, lounged again, no problem. Next I rode
with it loose, until I was sure he was accustomed to it, then just tighten up
every ride 'til it was actually doing it's job. Never had any problem at
all.