I run into a similar issue at work. I deploy ad-blockers on all student and staff machines. This makes our users invisible in Google Analytics. Supposedly our top browser is Mobile Safari.
My web filter blocks ads, but ublock is better. It blocks off-campus and handles first-party ads. It also hides ad content frames better than dns-level blocking does. It's also easy for users to turn off when some site doesn't agree with it. My network level ad filtering has to be simple to avoid breakage since it's harder to work around.
