Mine fits behind my license in a trifold wallet. Maybe your county issues a different kind? Mine is green paper that looks sort of like a library card with another paper on the back for the pistols that would not fit on the back side of the license. I think your wallet is the only sure way to make sure you have the darn thing on you.
I suppose you could find one of those ID holders and find some way to attach it to your belt and put it on with your holster, I'd be a little concerned about forgetting it personally.