While questing in Dun Argol, I came across a quest chain after you get theOverseer's Uniform
And doing that, I realized you can put this disguise on while mounted, and as long as you stay mounted, you won't lose the buff. Though, if you use it then mount, you will lose the buff. This makes for easy questing there.
I personally believe this is an exploit, but if not, I did not know.
EDIT: Can't post screenshot I already completed it and turned it back in