I have a Sous Vide rig. I put my dough in a one gallon plastic bucket and that floats inside a small beer cooler with some water in it that the circulator keeps at whatever temperature I want. A dish towel over top ensures the temperature is basically constant top to bottom. Proofing dough to within 0.1C accuracy is ridiculously overkill, but that accuracy comes for free. Works amazingly amazing.