Great work Creeky. I've got a little project along the same line as you on the way myself.... but in the mean time................ .....
you guys should check out this little write up on how to build a USBOTG box that not only enables USBOTG for US H300's, but it also doubles as an external battery pack/charger for the H300...... and you can make it for about$10-15 and a few hours of work:
http://reality.sgi.com/sawson/h320/
Its the first draft of the write up. I'll be cleaning it up a lot, adding a FAQ, ect.