@Damon102 ,
Forgive me if I'm incorrect but...
I believe asking for proof of military ID may be the only way to confirm that a person is actually a member of any branch of the military, however I don't think it's legal to ask for it to be photographed/sent over the internet.
Perhaps the Guest could present his/her ID to the Host at check-in, but I don't think you're allowed to scan or photograph the ID card.
How would you be able to confirm if the card is legitimate?
You may want to contact a military base near you for current regulations.
Good idea though, keep us posted.