I get you on the work thing. Fortunately, I work with a few very libertarian types, and the rest are not long out of college and generally overlook anything other than I-phones and such. I have spent considerable time honing an "old codger" atmosphere. Co-workers generally see me as a hunting type who does things "old school" cause I am too old to do otherwise. I am not that old, but it works for me. It explains why I tend to always have a knife on me, and why my daily backpack seems to always have just the right thing in it. "Why you ask? Oh just old habits from being a hunter I guess."
Seriously. If you really are a prepper, you will NOT fit in with the normal dopes in life. You are typically looking at things differently and have different interests. I know it sounds a bit CIA-ish, but developing a cover story (or stories) for your habits will significantly reduce the number of inquiries in the habits you keep. If you are confident and proud to be just enough different, most will leave you alone as our PC society tends to shy away from confrontation.
Study the people you interact with on a daily, or even less than daily, basis. What people would you expect to go to a gun store and buy a case of ammo and you wouldn't think twice about it? Who would go into a grocery store and buy 72 cans of black beans at one time and it wouldn't even rank a second thought from you? These are the types of people to emulate.
I imagine my UPS driver has a better idea of my prep habits than anyone else, but I doubt he cares in the least. Impersonal on-line purchases can help keeping things on the down-low. Unless you are concerned with paper trails. It is hard to buy from Amazon with cash. Just decisions you have to make.