I would have thought that a personal alarm clock app would have been running around by now. Like, you start it up, hunt until you see a mark die, click on the app to mark the specific target just died and the timer would start ticking on its own and beep/pop up and warn when spawn window opens and you just do it again to other marks until you have them all running. Sure, the spawn windows are large but from what I've seen, people have hunted for hours (only up 900 marks...3 week ago here).