Another alternative is this USB power port from these guys https://www.3brpowersports.com/products.php. I have the Tapp-HD and plugs into the Acc. plug under the seat. It's long enough to reach the handlebars on my King and powers my GPS and recharges my iPhone. It's also waterproof and panel mountable. Not too sure if it's long enough to where you want to mount your phone, but you can call them and they can make it a bit longer.