The topic is old, but can I recommend strongly symbolic and junction links for convenient backups. I am using this under windows.
A junction or symbolic link to the darktable config directory is placed in one of my standard backup source directories. From this source I am making manual and automated and versioned backups to multiple target backup directories (USB, NAS, other PCs …). With the junction/symbolic links it is easy to “collect” various important directories and files of various software tools (not only DT), which are distributed on different windows subdirectories.
Here is a good explanation about the various links:
difference-between-ntfs-junction-points-and-symbolic-links
Good backup tools allow the enabling/disabling of junction and symbolic links.
I am also using heavily the DOS subst command to map different subdirectories to drive letters. That is a good method for flexible file locations with constant drive letters. A different topic, but also quite useful for defined well backup strategies.