The obvious, best approach, I think, is hold any private business in harm, that invites the general public to their place of business, but demand that you disarm while on their property.
Its the immunities that harm the citizen. Qualified and absolute immunity for law enforcement and the courts as well as this, well, uhm, private property/business immunity for businesses. Get rid of them, and allow these people to be sued into non-existence, and the problem would go away overnight, once, sad to say, tragedy strikes.