I tried it, and it was OK, but in the end I turned the white LED to the front of the helmet . That will help me see my immediate surroundings and be seen. I also hooked a red tail light blinky on the back of the helmet by the front LED's strap.

So now I've got a forward white LED headlight on my bike and helmet, and red LEDs tail light on my bike and helmet. I think this will work well.