I finally got around to cutting my mat. I made three templates, first one was a 6mil poly, then transferred to a length of tar-paper, which I used that template to make another out of tar-paper to see how it fit. After some adjustments, I used that one to transfer to the mat material. I gotta say I'm pretty happy with the results.
https://goo.gl/photos/LFz1qk5xcJHxtYZv5And yes, I made this the full length, not just stopping at the seat riser and it will be tucking under the lower windlace strips, since mine screw in from the sides.
Now to cut my holes and get my pedals back in. I will also be doing this under and behind the seat.