So as you suggested Chashio I'm gonna try to do the border thing by hand! ..so i'm probably doing things backwards by putting on all the names and grunge, etc.. but I figured that this way I'd be able to work in a way that didn't mess up the map information rather than finding I'd destroyed the only space to put a name by folding up a corner!
What I am struggling with at the moment is marks for the ports. I don't want anything too fancy because I still want it to look pen drawn on ship as it were, I tried little flags and very simple hand drawn settlements, but neither look 'right'
...any suggestions would be gratefully received!