Why not follow Kovids lead and put them in the sigil config / plugin folder?
That way, There is only 1 Sigil folder backup that is needed to take
everything with you.
FWIW I just did that when My W10 SSD popped errors. I installed Linux Mint, Sigil, then copied the old config folder over. Sigil was up and running again in less time than it took to replace the drive (and install Linux)