Off the top of my head, as a Virginian within 10 miles of MD:
You can't carry openly, or concealed.
In a vehicle, if you are actually enroute to or from a legal shooting event, you have to keep the unloaded handgun in a closed container inside the trunk, and the ammo inside a different closed container inside the trunk. And a loaded magazine is illegal, being considered as a loaded firearm.
If your vehicle has no trunk, such as a van or truck, you are supposed to keep everything as far from your reach as possible.
When I go to MD for a GSSF or other shooting event, I keep an empty J-frame and a loaded speedloader in separate containers on top of my other guns & ammo, because that's the fastest way I know to go from Maryland-legal to prepared.
Maryland should be avoided in general.
Now let's see who quotes actual law sections.
Edited to add: I never heard of any non-resident or other permit to possess.