I am running pairs of Coast LED flashlights on both our bikes. Used only on the local MUP with some roads in daylight hours. We need the high-intensity flashlights to deal with deer on the MUP and joggers who do not wear blinkies or reflective clothing. You might want to look at Fenix mounts. Big and klunky but are durable and can be aimed up or down and right or left. I am also trying BioLogic FlashMount on my bike. So far no problems. Check the specs for what size (diameter) lights they can handle.

E. Ogre