What ever you decide to do, make absolutely sure it gets switched power. Most of those USB charger outlets draw at least 15-25ma(often more) all the time. They'll kill your battery in about a week. If you leave something plugged into the charger the draw increases to about 500ma. That's a lot.
Jaycar has a dual USB handle bar mount socket.Regards Martin.
I would say it is "water resistant" not water proof. The USB has a little rubber flap that will resist water.
If you are going to stay away from the Chinese stuff then get rid of your iPhone. Designed by Apple in California. Assembled in China. Says so right on the Apple iPhone box.