I plan to do decoction when the zombie apocalypse comes. With no electric, gas, or technology, just firewood, it sounds like the best way to do a step mash for all that under modified malt we'll be working with. When all you have is fire, I think you could estimate ground water temp and do the math on how much 212° to add to hit dough in. Then just pull the proper amount to boil and add back for the next step... etc. But till then I'll stick with single infusion and use cheap grain for flavor and color.