Well, I feel like I need to follow up with you all regarding the outcome of my "experiments" just in case someone in the future wants to reproduce or improve upon my efforts....
After a few days, the tinting material used in the "sandwich technique" began to sag and droop. Up close, it just didn't look good, so I tried to reapply tinting to the curved piece of plexiglass. Using a squeegee, I was able to get a very good adaptation to the plastic lens material and let it set up overnight. Unfortunately as the lens needed to be slightly flexed to fit within the mask, the tinting began to wrinkle in the center again. Unless you can get the exact curve reproduced, it will be a challenge to keep this material affixed properly.
So, I've resorted to ordering reflective lens material from http://www.motorcycle-superstore.com/11378/i/afx-fast-shield. I'll let you know how that goes soon enough!