I probably would've opened FV/Cutpurse honestly. This board is going to play fast, but with no real +buy, and a lack of real +draw, I think a variation of BM is going to beat an engine. Especially when you did yourself no favors by helping him amp up his cities. Note on turn 3, FV+CP would have netted you a gold, AND prevented him from buying his own FV (which coincidentally, allowed him to play both Hagglers later on, instead of just one.
He got a better jump with 5/2, no doubt - but you spent most your time trying to catch up and mirror, which ultimately just helped him more. Had you forced him to power up his own cities, his deck would've been stronger eventually (although without a second pile gone, not noticeably), but you could've gotten a good VP lead. Remember, All the Hagglers ok the world can't snag him free VP cards.