What you are suggesting should work, but you can also just enable un-shorted charging.
look into this thread:
http://talk.maemo.org/showthread.php?p=1431701

My best success has been to use an external to the phone charging circuit and connect the output to the N900's battery pins or use a shorted data pin Qi charger which plugs into the USB port.

In the end I find wireless charging is a great way to protect your USB port but it is difficult to get the device, even one with built in inductive charging to charge quickly and reliably.