Sailor, nice to be back and see this thread again. Once I went to primer cultures, I never looked back. You've my eternal gratitude for this, and so many other contributions.
Unfortunately, I'm starting over again. I'd like a water bath system that can do double duty - maintain the inoculated primer cultures at their needed temps, and a square configuration - i.e., not a stockpot stacked in another one - for cheese makes. The induction cookers I've found are over $200, will keep looking but that's a bit much for me, given that the purpose I'd have for the cooker is exactly as Sailor has laid out above.
Any food warmers I've seen - that would be controlled by a PID, as Yoav showed so well, or by John@PC's elegant solution - cannot handle a 6" deep hotel pan, so a 5 gallon tomme make is out (it took Pav reminding me one can, er, stack stockpots to get the benefits of doing makes with water heating). Anyone have any thoughts? Either an idea where to obtain an induction cooker that would do the job, but is under $100, or a square water bath solution, controlled, that could handle 5 gallons of milk?