I have to ask this.
Why?
I mean seriously, even if you carry the documentation around, it's gonna be a pain every time someone asks (and they will) and it seems like a lot of silly trouble to go through, just get a pair of safety glasses.
Yours may not fog up often, but they still might, and still may cause vision obstruction, plus its clunky and its going to make you sweat like a waterfall I'd bet.
I'm all for creativity, and having fun, but one thing I don't like playing games with is safety. Doesn't matter if they can stop a speeding tank, if they're obstructing your vision and becoming uncomfortable they're a safety risk in themselves and you shouldn't wear them.
These will work nicely:
http://www.amazon.com/DPG54-1C-Perfo...9293568&sr=8-1 they're only $3 + shipping and they're fully rated to the ANSI approval spec.
I'm sorry if I seem rude, I've just had a long season of butting heads with people over just wearing safety glasses, and I don't think this an area that deserves any flexibility, not even the slightest!
Compete safe,
Matt