Hi folks!
I believe I have a much simpler solution!
Just attach a pendrive and share it to EVERYONE. Open the guest VM and map the previos share using "net use X: \\HOSTNAME\SOMESHARE /persistent:yes" or using Explorer. Depending on your scenario, you may need to use the Host's user credentials.
After that I've noticed even the pendrive is not present, the share will persists in the guest machine! When the pendrive is attached, it will be available to the guest VM.
Regards!
Fábio Vieira