Get a note from God's mother.
Sorry for the sarcasm, but basically, you'd have to suck up to the Superintendent of the State Police and convince him that you routinely carry massive amounts of valuables in the course of your daily business in and out of the state or that someone in MD has/is actively trying to kill you.
Better to get well acquainted with a local sheriff and/or politically connected, make big campaign contributions, get them to vouch for your character and provide some sort of proof that you carry lotsa valuables and people are after you. It's only a little less subjective [ne:corrupt?] than CA.
FWIW, I own property in So MD, have looked into this a bit, and have decided I ain't likely to retire there.