Haven't used it myself, but I've looked into this one before:
http://www.amazon.com/Mounts-RAM-B-176--Double-Socket-Universal/dp/B00JUX1DRW/ref=sr_1_2?ie=UTF8&qid=1460706346&sr=8-2&keywords=RAM+stem+mount
It's a RAM kit that goes right into the stem.