Well DonDon, considering it runs off 12 volts, It seems it'd be very easy for one to throw an old cigarette lighter port in the same hole and then plug in the USB charger of their own desires.
2A typically is at the higher end of what they typically offer unless you pay premium prices for one that is more powerful. They tend to balk on that because they use terribly thin cable like 24 ga etc to bring the power down from the port TO your device and at 3A of DC, especially only 5 volts, the voltage drop tends to be HORRIBLE.
I suppose if one was handy with a soldering iron they could make one out of some 14 or 12 ga wire but still.
Better yet just get the 30 dollar 10kmA mini brick USB augmentator / portable charger, velcro it to your bike and run your GPS off that and just charge it every trip or leave it on your 12 Volt bus to keep it charged.
Aaron