Capacitive Sensing and Dielectric Coupling
I ended up using IPG carpet tape during testing.  I used that tape because it's pretty easy to remove and not as permanent as the 467/8MP stuff appears to be.  Long story short the transfer tape solved my problem.  The board is 6" long and over the length was able to conform +/- 1 mm in the z dimension with the help of the transfer tape.  The transfer tape did most of the conforming, no doubt.  I also added some mechanical features to help push the board against the surface, which helped the board/tape conform to the surface.  Problem solved -- capacitative touch is easily measured through the wood. I'll probably switch to the 467MP for fun now that I know that transfer tape seems to solve the issue (at this point the more permanent adhesion of the 467 is desirable.  I'll update if I notice any difference in performance).