when the image gets long appMeasurement code is supposed to flip over and send POST requests instead of GET requests. The debugger will show 'no requests found' in red text but if you go into developer tools on your browser and look in the network tab you will see a POST to you metrics server (instead of a GET) request for the image. You can then pull that request and uudecode it and find all the props/evars
I know I had (and still have in some instances) a list variable with several hundred entries in it and everything gets sent