Those 8 ports that I referred to earlier on/near the northwest end of New Guinea turned out to be "fake ports" - just a clump of graphics that "appear" to be shaped as port infrastructure would be (from zoomed-in map view), but no 'docks' or anything - and no ships near them.
There doesn't appear to be any rhyme or reason on types of traffic, density of the convoy or anything associated with where I am (within reason).
*sigh*
Oh well - enjoy trying out different tactics, approaches, weapons, etc. anyway.
"Nothin' to see here - move along!"
I haven't seen any troop ships in a loooong time though.
Maybe I need to be nearer japan, or in a MAJOR area - running largely stock game/sim, that is...