Update: Gave the markers a redesign, added indicators for the player being dead or carrying a flag, the markers now appear in Co-op, and other things. Check the description for details.

This does now require Network Script Resources, so be sure that you (and anyone you might play with) are subscribed to that if you aren't. Also, the host now needs to have the mod for it to work, since the host has a better idea of which team each player is presumed to be on.