People standing too close
In the lunch buffet room, I'm putting the food from the container on my plate, then scootch a step to the side, put some potatoes or whatever, then scootch again, etc. Right behind me, there's a person who stands rather close to me and moves immediately after my move. I'd describe it as pushing air in my ass, if you get the sense. Of course they're not physically pushing me, although the our elbows will on occasion bump into each other, and I need to think twice about how to turn around when lifting my tray (once I accidentally hit their hand and the food went all over the floor and on the person as well).
I've tried to handle it by asking the person if they could back off a bit so I could have the space. Probably a bad idea. Their hurry, enforced by my stress, is likely to perceive such a request as impolite and assaulting.
I've tried to move out of the way and ask the person to go ahead of me, (possibly pointing out that I recognize their hurry). Not well functioning either. Apparently, it risks to be taken as a sarcastic poke and the response is an agitated "what?! what?!" followed by an angry look and even more stressful waving me in to hurry up.
Embarking and disembarking the elevator
A similar issue at that office is people who lean into the elevator before others can disembark. Sometimes, I carry a cup of coffee. My knee has been operated and I have rather poor balance, so in this circumstance, I try to wait a few seconds for the person to back out of the doorway and let me off the elevator so I won't have go sideways. When that doesn't work, I back into the elevator and let the person/people (aka the wave) come in to the elevator. Then I go up and down like an idiot until I have a chance of getting out.
Sadly, that approach has also been aggravating to the wave and last week someone reprimanded me on the fact that I shouldn't have stayed in the elevator (the person realized that they kind of forced me to back in, and probably felt a bit stupid about it). The way I felt was that if I don't push my way back (causing annoyance) I will still fail by simply being modest (causing irritation).
What would be a good approach to improve some of the approaches mentioned above? Or, even better, what would be a alternative ways of handling them?
Note that I'm a large guy who's easily perceived as a threat or at least a physically substantial person (187cm, 115kg= 6'2", 250lbs).