I did something similar with deluge. Went an extra step and made a script update the deluge listen port.
Wrote down the details here if it helps anyone else. I included the docker config files and some issues I ran into.
https://edmomot.github.io/automatically-update-deluge-listen-port-when-gluetun-vpn-updates/






Gave FreeCAD and darktable a solid try hoping to switch my main desktop, but they have significant usability problems