I think i ended up with the exact same strategy more or less, but i decided to pick up vassals instead of merchants and sentries. I think that was a big mistake as it did increase my payload a fair bit, theres enough treasures in the deck to make vassal miss, or hit a terminal like council room or bandit, and that gets worse once i started greening. It was still enough to easily beat the bot though, since not having + buy or any way of scaling payload is just not good enough.