KlawMan et al,
It is indeed a Stock Positioning System unit. I plan to give them a call in the next couple of days and will ask. When done, I'll be sure to post the result here and give a couple of actual photos of the final positioning.
The good news is that, using the plate adjusted maximum low, my shooting improved and I hit a personal best 90/100 in 12ga this weekend. The disappointing thing is that another guy in my class managed a 92...and I was only one shot away from a perfect round. Still though...much better than my 82 average in a shoot just a couple weeks ago.