Thanks, Mark. I guess if I replace the Hero2, it might be a
Sony AS100 "Action Cam". It has a profile pretty darned close to working within N scale as-is (15/16" wide x 1-7/8" tall), and they say it has live streaming over WiFi.
I really like the direction these sport cams are going. I probably won't pull the trigger on this for a while, but maybe somebody else here might like what they see and report back.