Sadly, I made no progress in testing the idea of using the hibernation files as savegame files.

I have one more idea: use Acronis Partition Wizard (or a similar tool) to change the filesystem of your system partition to FAT32. Then you can play R:TW, hibernate, boot linux, copy the hiberfile to the location of your choice, restart, use Partition Wizard to change the filesystem back to NTFS, use computer for sth different.

When you are about to play R:TW again, change the filesystem to FAT32, start windows, hibernate, boot linux, copy the saved hiberfile of your choice back to c: (overwritting your "stub" hiberfile), restart your computer, play R:TW.

Sadly, I am unable to test this, since my trial version of Acronis Partition Wizard expired.