The error message in the event log is misleading. The missing "file hash" is really a Microsoft Root level certificate. I had my driver signed by GlobalSign ObjectSign CA which was a valid signature but I did not specify the cross-certificate which links GlobalSign to the Microsoft root certificate.
To clearly detect the original error I needed to use SignTool Verify with the /kp switch which tests for kernel level permissions needed by this USB driver. Using that switch I got an error clearly stating it couldn't find the Microsoft root certificate.
I downloaded the cross certificate for GlobalSign here: http://msdn.microsoft.com/en-us/library/windows/hardware/dn170454(v=vs.85).aspx
Using /ac switch with SignTool Sign I was able to sign the .cat file with a chain that went down to the Microsoft root certificate. This driver successfully installed on a Win 7 64-bit system. Victory!