Sorry, Alison, I only just saw your comment.

Network Proxy configs: I don't have trouble with it, but I also have a VPN available to me; maybe that gets around some wonky network setups. I have not had a problem in airports, universities, hotels, conference centers, or really anywhere that I can think of.

Test-drive Linux in store: I do this as a matter of habit. If I'm in a store with computers for sale, I usually reboot at least one PC to Linux just to keep tabs on what works out of the box these days. It seems rare for UEFI of display models to be locked down, so I open the UEFI UI, disable Secure Boot, reboot to Linux, test stuff, and then re-enable Secure Boot to avoid what would be vandalism (I have no interest in giving Linux geeks a bad name - "keep an eye on that one, he'll break our display models until corporate sends somebody to fix them") 

I've only been approached/reprimanded once for doing this. I calmly explained that I was testing Linux, which I require for work, because I was considering a purchase. The salesperson did not stand down, so I calmly rebooted and later sent an email to the store manager telling them that Linux is a real OS that real people in the area use at work, so the sales team ought to be made aware of it. I haven't had a problem since in that store (Warehouse Stationary in NZ, for the record). 

Otherwise, no one has ever bothered to approach me about it. I guess if I was nervous about it, I might try to find a sales person and explain what I needed to do, and why, and then ask if I may demonstrate the process, walking them through everything as I did it. Throwing fancy words around, like "programmer" and "software developer" and "C++" might help dazzl le them into submission.

Either way, it's worth a shot.