Just to clarify, you aren't under any report obligation for a GS, at least as long as you don't check the "automatically notify me" box. Not sure how that would play out. But for any other GS, they call you and you say where you are and how long you need and its their problem to figure that out.

You can answer with impunity as long as you're honest about where you are and how long it takes you to get there. If you're in PTC with your bags packed or scuba diving in Kuala Lampur so be it.