Sure you can! One question would be do you need to access the game files from 2 or more systems at the same time? Then it does need to be a share. qemu does have a built in samba system of sorts with share option in the storage section, but different vmm versions have different options, and that's going away with virtiofs coming.
But, if you work on the game files exclusively from one instance at a time then a virtual drive works better than anything. Convert the game files to a qcow2 or img(raw) disk image file. Mount it where you need it when you need it! You can keep a compressed qcow2 file as a backup - might not be 40GB's!
You can use the command line, convert those into button actions in the host UI, or use VMM.
I assume Win7 will act like XP, so you can actually hot plug the sata bus and a drive image to a running vm. The machine type should be a Q35 and Win need the drivers already installed (9DO sata I think). Or use USB as the device bus, slower. The first time win might want to reboot, but subsequent times it is hot pluggable. User error is a concern - don't forget where it's mounted!
Obviously this virtual drive needs to be NTFS for windows.
There is obvious overhead here that makes it sluggish on a weak computer. If a qcow2, the system would like to have a few free cores for the compression stream, etc. On a powerhouse machine it's very transparent. Such a drive could be much smaller than the 40GB depending on comprehensibility, again a few spare cores please...and with use the image file will grow to uncompressed data size -and even slightly larger. You can use standard tools within any OS operating on the image, and occasionally when not in use use virt-sparsify to 'trim' the drive image, then copy to a new file with compression to start the image fresh again and at maybe half size. As an example, my OS images average 1-2GB, an i386 32GB image with wine and more than 10GB of game stuff - last refresh the image was 7.8GB! A drive of photos is 10%+ smaller, my records drive is 80-90% smaller, etc. They are available to any vm and host - just not concurrently - and best of all they can be 'off'.
I do this with nearly everything, actually everything. In this format it's easy to keep a backup, it's a single file - so it's like a big file, still just a file. Each OS I have has a qcow2 file backup, even windows. Many things compress down pretty far, you're familiar, and even things that don't you are still eliminating slack space in the filesystem. Qcow2 is very mature and reliable. I did a post awhile back device=disk=directory=file or something like that, this is what I was talking about. Commercial use includes virtual drives in the hundreds of GB's. With this technique ransonware is a hour inconvenience at most.