I just met a truly ingenious baker at the Toledo (Oregon - a 10K pop mill town) farmers' market. He has converted a small van into a mobile bakery, jury-rigging most of the equipment himself.
He has an old 3 deck oven with steam injection from a cup of water coupled with a windscreen wiper device activated by touching 2 bare wires together; a retarding /refrigeration unit worked by an old single room air conditioner; a home rigged proofer and, the only new commercial item, a Globe mixer which is the pride of his life. All the non-standard equipment runs on 12V electricity!
Most of his products are sourdough & he sells 2# sandwich loaves for $3 to make sure children in this economically depressed area can afford good food. He is a great enthusiast and a tribute to American inventiveness!