How to disable proxy caching with .htaccess

Question

I have a problem where corporate proxy servers serves up the page for different logged in users. I reckon I can solve this issue by disabling proxy caching. This page suggests including the following snippet in htaccess:

ExpiresDefault A0
Header set Cache-Control "no-store, no-cache, must-revalidate, max-age=0"
Header set Pragma "no-cache"

As I've understood it (by Googling), the Expires header is only read by proxies, so I might also just use "Header set Expires 0"?

I suppose this would also prevent caching of stylesheets, images and other assets (although only by proxies, not browsers)?

What is the best way to deal with this? I'm running PHP, and can easily modify headers through PHP, too, if that's recommended.

I don't have access to a proxy server for testing.