Tricks for keeping glass from fogging up racing on cold nights?

I had mentioned glycerin way back, cuz it worked for us "back then" - - from a pharmacy for a few cents .
Someone mentioned shave-cream, but it's messy and if you are using Lexan, you will scratch the **** outta it, trying to clear the cream.
You know what, - shave creams ingredient is "glycerin".
My mentor used to say "suit yourself", pronounced "shoot yourself" when I chose an alternate method , he was usually right.
Mind you, - he was never wrong, - even tho he wasn't always right.