Just for encouragement: Aftern running Earth Panzer close to 30 times on insane with 20 odd golden chests - no hit. Today Water Panzer comes up, I give it a try and with a single golden chest claim the prize.
Setup was using blackbeard instead of cyclops and cost me 3 revives en route (1 on stage 6 and 2 on the final stage) with a total of just over 10k hp.