Agreed, lighted fishing boats and junks would be nice.
I've read various sources that describe how these were encountered by US subs, one such source is USS Segundo's patrol log, linked below, that mentions seeing occasional lit up fishing boats and lots of fishing boats in general while patrolling off the southwest coast of Kyushu/Tsushima Straight in early 45. A good read.
http://www.segundo398.org/patrol_reports/patrol3.pdf