In several states, carry permits are a form of affirmative defense. That is, you're assumed to be engaged in unlawful activity until you can prove otherwise, usually by producing documentation. However, law enforcement isn't bound in such cases to accept the documentation. Affirmative defense is generally applied at the trial level, not the arrest level.
If you are going to carry, all it takes in any
states is one overzealous LEO for you to take a trip to the county jail. Besides copies of the law, it is a good idea to have the number of a Pro 2A attorney handy. Even if your state is as pro gun as it gets, all it takes is one LEO who doesn't know or understand the law and at a minimum you are in jail for a few hours, your car towed etc.
Honestly, I think getting your lawyer on your cell phone is probably more of a deterrent in this day and age than a copy of the law when it comes to staving off unlawful arrest on 2A matters.