No offense, but your Second Amendment rights end when you enter onto private property.
Your RKBA rights do not trump my rights as a property owner and like it or not, they never will.
The Constitution was written as a tool to protect citizens from the GOVERNMENT, not from each other.
I own and operate a small business that is open to the public and I do not post signs promoting nor denying CCW.
However, it is MY right to decide how I manage my business just as you have the right to spend YOUR money elsewhere.
"Voting" with your wallet makes more of a statement to a business than any letter, no matter how polite or well-written.