So I think the difference is the articulation of the hinge for the stowed position. The Mounty boards, as you appear to know, are flat, thin and they look wider than the Exp boards. Our boards are shaped kinda like a boat if you view it from the front or back.
My thoughts, for what they're worth is that because we know the body of the Mounty and the Exp are the same, these boards will work. You'll probably just want to get both sides so they match.
I'm assuming you're eyeing the ones listed for around $400 shipped.
For what it's worth, if you think the actual hinges can be broken down and repaired, I have the left side complete except for the board. The motor/trans is junk, but the hinges work perfectly. I'll let it go cheap if you're interested and I'm local so no shipping. PM me if you want to explore (pun intended) that possibility.