Interesting, but this is not a military situation, so I am not sure that "atrrit [sic] the enemy at the maximum effective range of your weapons" works for bums. As for involving "weapons (guns or knives) access," I think you are asking for legal trouble if this is done merely because a panhandler approaches asking for money. Your gun is not for keeping bums at 12 feet. If he keeps coming, are you going to shoot him?
One of the things I teach in my more advanced classes is that posture, voice, and non-verbal communication are primary weapons in dealing with others. Students have to go through a repetitive role play with me.
Me (bum): Can I ask you a question?
Them: NO!
Me (bum) But I just want to ask you a question.
Them: NO!
Me (bum): I just wanted to ask you a question. (dejectedly)
Them: NO! STOP! DON'T COME ANY CLOSER!
Me (bum): You're no fun. (walk away and wait for next pigeon)
While this is going on, I am slowing incrementing (getting a little closer). They are supposed to back away and maintain their
flight initiation distance (The distance at which an animal will flee from an approaching predator) as the interaction is going on. I don't want their feet glued to the ground.
It's surprising how difficult this simple exercise is for many people. When I was at Deloitte, the firm sponsored a self-defense class that had both hands-on and role play components. Sixteen people took the class. For one of the role plays, the instructor clearly laid out the boundary at which we were to say "STOP! DON'T COME ANY CLOSER!" I was the only person in the class who was able to do it initially. A number of people required several iterations before they were able to say it at all. Deloitte employees are universally nice people who are used to being in the collegial atmosphere the firm fosters. It's hard for people like that to transition to effective boundary setting when dealing undesirables. It requires practice and regular reinforcement.
I personally also include "ALTO. NO ME ACERCA MAS!" (Spanish for SDCAC) in my repertoire because of the large Spanish speaking populations I have encountered but don't require it of my students.
The incidents involving weapons were clearly not just bums asking for money. They and I both knew it and we began the interaction accordingly.
There are two key boundaries, as opposed to zones, in proxemics that are relevant to self-defense. The first is 'flight initiation distance', the second is 'critical distance'. The term 'critical distance' was initially presented by Dr. H. Hediger in his book
The Psychology and Behaviour of Animals in Zoos and Circuses as the distance at which a pursued animal will turn and initiate a counterattack on the pursuer. Dr. Hediger posited that both 'flight (initiation) distance' and 'critical distance' have very specific quantitative aspects that are species unique. Dr. Hall, the founder of proxemics, felt that flight and critical distance were no longer present in the human species but I believe this is incorrect.
In self-defense, the key to avoiding necessary physical violence by the chosen victim is to keep the predator beyond critical distance. My interpretation of critical distance for North American urban humans is that it usually occurs somewhere within the near phase of social space (4-7 feet) as defined by Dr. Hall. This is not to say that it cannot be triggered at further distances by events such as receiving gunfire or making violent and tumultuous entry of one's dwelling.
The best way to keep the predator beyond critical distance is to begin
communicating at our flight distance, which I interpret as the far edge of social space (12 feet). That's the point where we begin using our verbal and non-verbal weapons so as to get de-selected by the predator. I.e., we are using non-physical weapons to attrit the victim selection process and get the predator to move on to someone else. It's somewhat akin to the joke about two people being chased by a bear, one of whom says: "I don't have to run faster than the bear, just faster than you."