Okay, so here's the ironic thing:
If we want to construct a merchant spy network, the number one thing we have to be
at this very moment and in the near future is accessible to merchants. This is because the way agents are usually created is not through blackmail, but through some combination of "money, ideology, ingratiation, disgruntlement, fantasy, self-importance/ego, and kinship", as a non-exhaustive list.
Remember how we made the big "mistake" of preaching about giving a single flying fuck about civilians a couple chapters back? Remember how we are the scions of the Land of Fire's Hokage? Remember how the implication is no other villages give a single flying fuck about civilians?
Without even trying, we've managed to hit six out of the seven conditions to any-wannabe spymaster of great import who will help out their friends.
Now what we need to do is give them an opportunity to sell themselves out, and we'll be able to rake in hilarious amounts of intel;
much without paying a single cent.
To this end, I'd actually advocate a bigger victory tour, one that just so happens to take us near the merchant trading hubs near the borders of Fire and one whose destinations have been consistently leaked (because we're supposedly hitting every last one) and which has about a billion different itineraries, so that we'll also tie up chunin to ANBU level resources for a literal month as every single other nation races to keep us out.