Since its a Constitutional right, states should not be regulating, and any license should be like a drivers license, recognized Country wide.
Not that there should be any license for a Constitutional right mind you.....but I understand baby steps it takes to get there.
If we're going to compare to drivers' licenses it seems there's some conversation to be had in parallels. (Bearing in mind this isn't my preference, just an hypothetical.)
So, you have the right to move about the country, but you don't have a right to drive an automobile, yes? This is (in my understanding) the argument for licensing drivers and coordinating the interstate compact that sees their recognition nationwide. Those agreements say it's incumbent on the driver to know the local laws, e.g., passing on the right, or right on red rules.
Similarly, one might say we have the RKBA, but that doesn't necessarily extend to all arms in all places. If we accept that, and assume the states behave reasonably, we might imagine a reasonable scheme for ensuring a person who avails himself of the right is doing it within the state's agreed structure. Then we could reasonably assume the states would, on their own accord, come to some agreement where they respect the LTCs of the other states.
If we hold to the ideal that that government is best which governs least, it seems appropriate for the feds to try to be hands-off here. They've been shown that their previously light approach was insufficient to endure our rights are protected, so they've now provided updated guidance. Small corrections seem better, even if it means we still have to get beat up a bit before we get where we're going.
The alternative is a fedgov that regularly takes too-big bites and we find ourselves fighting for 88 years to overturn another Miller Decision that went the wrong way.
Or maybe I need to go eat lunch and stop giving the state too much line.