400 miles is a relatively short trip. Are you needing to make calls or use the phone as a GPS? Or?
My Triumph has a power port that accepts a BMW-style plug that interfaces with my cell phone charger. Everything lives in the tank bag. Sometimes, I might even power up the phone for a couple minutes as I did on my last run to Mexico. Called home and told Wifey I had arrived. For my Airheads, the phone goes in my jacket pocket and stays in the off mode. If you get the idea that I'm a novice Luddite, you'd be correct. I ride to get away from this stuff. Paper maps and a route sheet spell Oldskool.
You might check in over on the ADVrider site. Those guys have all the latest electronic gizmos.