sorry in advance for long answer...i don't have/use a map board bc i don't nav usually. on my gravel bike i made a
cue sheet holder out of a plastic clip, some pipe insulation, and zipties.
my team's navigator uses a similar set-up, except his clip is permanently attached to his stem with a bolt. and his compass is glued on an upside-down plastic spatula.
that's what you get from us hoosiers in St. Louis, MO :)