http://ciisqbg45nggykdl6rjdrq3wc64csga4vkphu66qsi65mypeitqedoad.onion/pfsense
If using IPv6, repeat the previous step, but select IPv6 for Address Family, and 2001:db8::7 for the Address (or 2001:db8::8 if you don't want ad/tracker blocking). These rules should force all DNS requests to get redirected to the VPN's DNS servers.