Approached by a homeless aggressor

Scenario:

You've visited someone in the hospital and are returning to your vehicle in the large parking lot that at that hour has very few vehicles parked there. It was full when you parked where you could find a spot, but now it's sitting out on the open with no vehicles near it.

As you're crossing the lot with good SA, you spot what appears to be a homeless man who appears to be in his 40's or maybe 50's hanging around the peripheral of the lot. As you keep an eye on him, you notice you're now the object of his attention as he's now moving to intercept you in the lot or at your vehicle door.

He has no visible weapons on him, he's not carrying anything that could be used as a weapon expediently against you. Before you can get the car unlocked and enter and lock the doors, he's now within 6 feet of you and closing. He's not threatening you in any verbal way, but it's clear he's not going to give up the chance to ask for and get something from you [ usually money ].

What's your response going to be?

Confront him verbally to go away, back off, leave you alone?
What if he continues to aggress on your person?
Will you allow him to get closer than that 6 feet?
How will you enforce that distance if he moves closer?
Threaten grave bodily harm or death upon him by announcing your armed and will defend yourself if he closes on you?
Can you even draw and fire your sidearm before he can reach you and wrestle for the firearm if he decides to?

Now, he's closed to bad breath distance, you're continuing to tell him to move off/go away and he's ignored you and you've done nothing but verbally warn him to not approach. Is he an imminent threat of grave bodily harm or death to your person. If he's not, will you still draw your sidearm and threaten deadly force use if he doesn't back away and leave you alone?

Interested in hearing what others would do based on their strength, infirmities, skills sets or lack thereof.