The key here is avoidance of a situation where the advantage of surprise would go to a potential attacker.
When in parking lots...walk down the middle of the lane, so as to avoid a sharp corner where you could be grabbed unaware.
There are volumes of words written on that subject, so I won't further abuse that dead horse.
So, let's assume for a moment you find yourself in a situation as you describe.
1. I carry 5-one dollar bills in a 99-cent money clip. Mas Ayoob (I have been through LFI I &II) advocated this years ago as a strategy for "buying off" thugs who want to appear tough. "Here fellas, I don't want trouble...have a beer on me." If you are forced to use deadly force or even draw your weapon...IT LOOKS FANTASTIC IN COURT. If you don't have to defend yourself...five bucks is worth it not to have to shoot someone. As a cop, I never carried the money clip, but I do as a matter of habit as a civilian now that I am retired.
2. The dummy wallet is a good idea. The money clip also serves in this role. The truth is...if a d-bag has my wife or daughter at knifepoint and loses his concentration for ONE second while going for the loot...he is MINE. Period. Again...it will look great in court, if you are charged, that you did all you could to comply and end the situation without bloodshed.
There is no shame on your manhood. It is called planning. Heck, if you find yourself in a fair fight, your tactics suck. Give yourself every advantage. In my career as an officer, I was involved in 2 shootings. I can tell you, neither was without it's nightmares...both legal, though totally justified, and from the standpoint of having to take a life. I know how I would react if faced with similar situations again.
I take the safety of my wife and daughter most seriously. There is nothing I wouldn't do to bring them home alive. My wife also carries, and we have plans for home invasion and situations outside the home.
PLAN PLAN PLAN.