There are browser add-ons for disabling GA. your support team could use them.
http://techie-buzz.com/how-to/how-to-disable-google-analytics.html[^]
Edit: Option 1 is the best I think. the filtering shouldn't be too difficult as your internal IPs should be easy to identify if you are running on private address space or all addressing internally appear on the application from a single Shared NAT gateway address.
Option 2 is also an option, and the support team just need to be educated to make sure it is part of the test procedures and they get it into their heads to switch
Option 3, i would avoid, involving more settings (particularly those that could be found and turned off by the customer).