Very nice job. I have an idea for the nav map:
You could use the free space for some info charts. I just copied the distance charts from gwx inside.
Same thing with the view of the barraks: just show some infos about the ranks, batches and so on.
Or at the view from the sub in port. There you could show info about the different subs.
Depending for the megamod you build the gui for, you can show nearly every interesting info around the screens, when the size of them is hard coded by sh3.