(Solved, explained in the post)
I'm trying that right now, but I can't figure out how to decrypt and mount my drive at boot, I've read that simply giving the drive the same passphrase as that of the first drive would enable unlocking both at boot (reference), but it didn't work for me, the drive remains encrypted and also not mounted despite me adding the entry to /etc/crypyttab
and /etc/fstab
That sounds promising, but I feel like it is quite complex for me, maybe I'll look into it again another time, thanks for the suggestion and explaining to me though!