[...] the Peddler doesn't seem to do anything here; except to give 1 extra coin and a pile to end the game on.
When I tried to modify CC's solution, I thought that Peddler has no function either, but in the beginning of turn 4, he uses a Procession-Fortress to draw two cards and gain a Procession. One of the drawn cards is the Peddler, which is used directly afterwards to draw the gained Procession. If the Peddler were not bought, you could not have used it's cantrip effect to draw the Procession. It's incredible how optimized his solution is...
Nevertheless, I think, it is possible to replace Goons with Fairgrounds and then using the Colony buy to push them to the next level -> 30VP.