I would like to make sourdough starter and have read several webpages with "how to's". There are several good sites with very detailed instructions, but I have one question. They all use a relatively tall bottle to make the starter. I would like to use a square plastic box - relatively short, but long and wide - to make my starter so that I can put it in a bigger box full of water. The bigger box will have an aquarium heater in it set to 83 degrees. My kitchen/house is usually 65 degrees 16 hours of the day, when I am gone so I want to find a reasonable solution to creating an environment with a stable temperature without having to heat up the whole house. Will this work? or does the culture need to be "stacked tall" to reproduce well? Is plastic ok to use?