I got tired of waiting, and picked up one of these:
http://cgi.ebay.com/ws/eBayISAPI.dll...m=290321136790. About 10 minutes with the dremel, and the USB connector was relocated to the right place. This was even easier to modify than the HTC G300 cradle appears to, as I didn't need to cut the ballast/weight. I also specifically wanted the extra battery slot this cradle has, which is why I opted for it over the G300.
Many thanks to chris1683 for the inspiration. See his thread for details on how to modify the HTC G300:
http://forum.ppcgeeks.com/showthread.php?t=90846. Keep in mind that the steps will be slightly different for the eBay cradle, but the idea is the same: enlarge the opening on the top panel to move the USB connector to the left, modify the plastic fitting that holds the USB connector board in place, reassemble.
George