An interesting discussion, @Michelkeijzers, on this is going on here: Lights out / headless GP system?
But concerning your specific question: How I did it was
- to sync, load and check the files I used a remote desktop app on the tablet that serves and my OSC controller during the gig
- for situations where remote desktop doesn’t work (BIOS etc.) I had this (15 €):
Of course, you’d need a screen, too, in this case. For these emergency situations I would have used the TV screens that we happen to have on stage.
Did I ever need it? No, but it gives you a good feeling.
I’ll add why I don’t want a headless gig file any longer soon in the other thread.