Something I have to soldier together with electronics and a circuit board is out of the question. I am confident someone makes the type of lights I want. It's just a matter of finding them.

Hand signals do not work. At night cars cannot hardly see them and most drivers don't know what they mean anyway. A bright red light will tell them I am stopping. A hand signal will get you run over with a good change of getting your arm ripped off. I find most cyclist naively rely on hand signals too much and take for granted that the driver behind him will know what it means. That's just Not safe or smart.