Kuryakyn also has a 12 volt cigarette lighter option in chrome. To get USB out of that, you just need a little 12 volt to USB adapter that fits inside it. And then you have a 12-volt outlet right on the handlebars for compressors and whatnot. I went that route personally and has worked great for a few years.
Electrical Power Point | Device Chargers | Accessory Mounts | Kuryakyn
Plus something like this:
The adapter fits neatly inside the power point and you can close the rubber cover with the USB adapter inside.
The power point should be wired to a fuse box, of course, and only provide power when the key is on, just to make sure there's no power drain when the bike is not being used, goes for any accessory like this I'd say.