I am looking at different set ups, and honestly an thinking I will use a plastic tub. My question is for those using plastic what heating do you use? The areas ambient temp is fine (it's an addition to the house so it's not on the central air and stays warmer) and I can always mist if I need more humidity, but I need to have a belly heat area and have no clue what to do about it cause all the heating pads I find say not to use with plastic.