Connect IQ workout player app on Edge 520 on an outdoor ride

Is it possible to use the app within (i.e. as part of) an outdoor ride? That means: start an activity (press the Edge’s start button), then ride for a while (no workout started yet), then start the workout on the Xert app, finish the workout, continue the ride (still logging the activity) until I stop. The entire ride then should be saved within a single FIT file.
I did only one outdoor ride recently using the app and it seems that it’s not possible to start the Xert app once an activity has been started (by pressing the Edge’s start button). But maybe I did something wrong…(?)

Once an activity is started, you cannot run the workout player. You can however record a regular FIT file using the player. Simply select START LATER on the menu when the workout is loaded.