I think all your ideas sound really good, but one of the things I liked best about the jacket is the height of the lights. I often ride with stuff on a rear rack, and with my short legs, that means the back of my saddle is obscured. A light on the back of the rack is too low in height to be effective in traffic. The jacket's advantage was that it was on the persons body... Of course, this won't work with a back pack, so I guess all designs have some downfalls. Perhaps on the back of a helmet? Then long hair or a helmet cover could be an issue, I guess...

I don't know...just thinking out loud here....