Maybe this question can be best answered if we understand WHY you want the hoodie to go over the helmet. What are you trying to accomplish? Why over rather than under? Why a hoodie? Why is the cap you use less satisfactory? Is it because you wear a hoodie as street clothes, and you want it to be useful and not bother with the separate cap?

Some people will say I'm all wrong here, but if you're going slow enough that the hood billowing out like a parachute isn't an issue, maybe you aren't going fast enough to need a helmet. Seriously - plenty of people can run 15 mph and no one says they need to wear a helmet. The restriction a raised hoodie places on peripheral vision is a much greater safety hazard than the lack of a helmet at casual speeds.