With the current script that can add a job to WebPageTest we can either send the data to statsv or output it as JSON. A small change could add the functionality to output a CSV comma separated line with all the metrics, that will make it easy for us to compare different runs when we do some tests on mobile.
ah sorry, my fault. What I meant is that we can use the thing we use for testing desktop/mobile right now, a command line tool that submits tests to WebPageTest (https://github.com/wikimedia/performance-WebPageTest). so you still need to do the work, but testing and automating the test and collect metrics is easy.