As a way to address the registration problem with the above paper, and an attempt to bypass the Yupo - 3M adhesive solution, I shrank Masa in room temp water, mat face up after wetting both sides.
A 90 min shrinking was reasonably effective and did not abrade the surface. A 12 hour shrinking was detrimental to its integrity and coated unevenly with the cyano emulsion. I will shrink for longer than 90 min to see if it will permit even more accurate registration and report.
Incidentally, 3M have responded to my request to help me with the most appropriate product to use for affixing Masa to Yupo by asking me for more detailed info. I am hoping that I do not have to go the Yupo route, though it was a good thought!