Just in case you want to do something similar: To get an "Open Terminator here" right-click action into Nautilus (the file manager) I used the program filemanager-actions-nautilus
from the repository and configured it like so:

and called that "Open Terminator here"
I'm sure that there is also a hacky way to get the standard "Open Terminal here" to open Terminator instead of gnome-terminal, but I haven't looked further into it after I arrived at my mediocre solution.