I could be mistaken, but I don't think even that would be sufficient? Before would make your command execute before the network is brought down, but it wouldn't have the latter wait for your command to actually complete.
The post shows long-running stop scripts / containers and demonstrates them delaying shutdown (not with KillMode none though)
@CGamesPlay network.target's "primary purpose is for ordering things properly at shutdown: since the shutdown ordering of units in systemd is the reverse of the startup ordering, any unit that is order After=network.target can be sure that it is stopped before the network is shut down if the system is powered off."
