I use a virtual machine with all traffic routed through a VPN as it provides far more isolation than a container.

You can bind qbittorrent to a network interface (vpn interface) so it only puts traffic through it which prevents leaking traffic.

qBitorrent + https://github.com/qdm12/gluetun

https://github.com/haugene/docker-transmission-openvpn

This is what I use. Really simple to setup. It has a kill switch in case the VPN goes down.