Provide two PAC files to the Sauce Connect client. One for the traffic generated during a test and the 2nd PAC file for the initial setup of the tunnel. All of the REST calls and traffic to allocate a tunnel should go through PAC file 1 then all of the test traffic after the tunnel is allocated should go through PAC file 2.
For example if a shared PAC file must be used internally but must be treated as a read-only file:
./bin/sc --i my-tunnel --test-pac file:///my_user/sc_stuff/traffic.pac --setup-pac http://my-company.com/shared-location/setup.pac
This would allow a clear division between the traffic for the initial tunnel setup vs the traffic generated from the app/site under test.