Fortunately, I carry a couple red light sticks and paracord for a lanyard. The light sticks can be used for both light and signaling.
That is one of the most underrated night time signaling methods. A strobe is great, and has the added benefit of being passive. But, a simple $0.99 chem-light and $0.25 of paracord is a very effective signal… and the red chem light is probably just as visible as that cell phone’s screen.
Red is a good color choice too, visible though NVG equipped pilots using the –blue/green filters.