These are all great resources, and I use them myself (especially handgunlaw.us) BUT ...
they are not the actual source of what the law is.
If at all possible, in addition to checking handgunlaw.us, I would go to the website for the state police and/or state government for the places you'll be passing through, and get what you can and print it out to bring with you. Some states' information is easier to find than others, but info from the government itself is better if there's a disagreement or interaction with local law enforcement. Handgunlaw.us saying you can do something or don't have to inform the LEO you're carrying, for instance, carries less weight than something from that state.
I've never had this come up out of state, but I try to be ready in case it ever does. Similar to how I print out airline and TSA rules on guns in baggage vs. a summary that someone else made up.
