Ok. Not sure if anyone has said this yet or not so here goes.
MD has been known to pull cars over with plates from shall carry states. And they have asked to search the car. Of course you should respectfully decline if this happens.
The last time I checked MD has some odd laws when it comes to transporting firearms. You may transport them through the state and you may transport them into the state to your domicile (which includes a hotel) or to a range or hunting.
But to be legal the guns must be in pretty much the same condition as they are when yuh check them into an airport (minus the locked gun case).
So gun must be empty with no loaded mags and Ammo should be stored separate from the gun. And they must be either in your trunk or in the bed/toolbox of your truck. Once you get to your domicile, range, hunting trip you can then load your weapon.
That is, if you want to make sure you are legal in the state.