My contribution to this thread is a simple one compared to most. Just bring back the calender with the historically accurate moon phases and important dates. Maybe include local sunrise and sunset. A calender existed in SH1 and 2 so it seems likes it shouldn't be too difficult to re-code.
It's not like I'm asking for the moon...I just wanna know when it's full.
Oh...and make harbours less of a pushover. They always seem to be hopelessly under-defended.