Not sure if you're looking to keep only to foss solutions, but if you're OK with a proprietary driver (and as you're on windows anyway), the ext4 driver for windows from paragon sounds like it would work well in your situation. You can install it on the windows machine and it'll mount ext4 read/write like any other windows-compatible drive, complete with automount. They give you a ten day trial to try it out, so you could test it a bit first to see if it'll work ok with OBS, then it's twenty dollars USD. Not advertising for them, but I just went through this process myself for an ext4 external hdd earlier today and wanted to share. :)
Not sure if you're looking to keep only to foss solutions, but if you're OK with a proprietary driver (and as you're on windows anyway), the ext4 driver for windows from paragon sounds like it would work well in your situation. You can install it on the windows machine and it'll mount ext4 read/write like any other windows-compatible drive, complete with automount. They give you a ten day trial to try it out, so you could test it a bit first to see if it'll work ok with OBS, then it's twenty dollars USD. Not advertising for them, but I just went through this process myself for an ext4 external hdd earlier today and wanted to share. :)
https://www.paragon-software.com/home/linuxfs-windows/#