After many years of using buffet pans I'm looking to upgrade to a real maple syrup flat pan. Can you remind me, is the evaporation rate still going to be determined by surface area? I'll be boiling with wood, over blocks w/ fire bricks. I could hit 8-9 gallons/hr on 5 buffet pans (24x12x4). What size pan should I get to stay around 8-10 gallons an hour? I would like to get a smaller pan but 5-6 gallons an hour is slower than I'd like.