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How can I access a Windows mounted drive from a guest Linux VM without sharing over the network?

Environment:
I have a Linux web server running as a guest VM (Hyper-V) on Win 10.
My web store is now requiring 100+ GB for repetitive image files.
Because of this size, I can no longer back this up locally to my local backup repository and would rather back it up straight to my online backup.
The catch with the online backup is that it must be a mounted drive in the Windows VM host. Sharing the files via the network creates access delays for people accessing the website. Using a virtual disk on a Windows partition will cause the backup to upload the full drive every time the file changes wasting bandwidth.

The only option I can think of is to use an iSCSI target and connect both OSes to it. It doesn’t seem like a practical solution and may create access delays again.

Is there any way to have a drive “mounted” on both OSes or share a Windows VM host mounted drive locally via Hyper-V?