People buy prescription drugs from Canada that are delivered in unmarked boxes. I bet you could get them.
For fun, I once bought doxycycline (for an acne problem) from Canada without an rx. It arrived a couple weeks later in a discreet brown cardboard envelope. It had been shipped to me directly from India. Very interesting. I looked up the pill in the PDR, matching the PDR poto with the pill in my hand to verify it was truly doxycycline. Cleared my acne, too. To be clear, I just wanted to see what would happen, if I could REALLY get something without an rx. I could apparently.
Granted, that was borderline illegal of me. But I can rx orals. If caught, I could always produce an rx for ocular rosacea and get out of trouble. I actually have a mild case of it legitimately. I know, I'm justifying my naughtiness. Actually, for that drug, it was more expensive ordering it from Canada than just getting a generic here! I wouldn't do it again though.
With regards to lens, I'm sure you can get it. It would probably be handled and shipped in a similar fashion. Safety-wise ... if you are willing to take the risk then that's your choice. I don't have any experience with this lens.
The US has lots of laws and sometimes I question them myself. Like ... is this lens worse than heat-tempered glass???
If it is prone to shattering, you may want to order several blanks in case it breaks during edging or mounting. But ... does a high-index plastic-type material really shatter? I thought only glass shattered. I thought plastics broke in chunks.
Does anyone know how this lens compares to heat tempered glass lenses in terms of impact resistance?
Anyway, good luck, I guess.