We have had no deaths so far, and I can assure you that we aren't optimised (the Cleric has Negotiator and Skill Focus (Diplomacy) for pete's sake

And we have a Mountebank. Our main tank is a Ranger and our mage is a one-trick-pony Illusionist). What we have going for us is that my character has high Int and my strategy is fairly good when I play up the Int--that can be a big difference (For instance, I hear the Worldwide D&D Gameday was often a TPK and almost-always had several deaths, but I led the group to a victory with no deaths, even the god-awful Paladin with the 10 Cha).
For Life's Bazaar, we didn't go the way with the hammerer/illusionary wall, I think--wait, is the Hammerer like the Pulveriser construct? My character thinks those are cute--our gnome commanded them to stop and then my Archivist brought them up to fix them. The way we went was from the room with the haunted statue where you use Sovereign Glue up to the barracks of the hobbos and then sideways into the room with the BBEG and his pet.