I follow Jerold's routine as well. There is no need to fill the reservoir higher. Given time, the solutions will come to temperature. In the warmer climes ( although one would not know that Florida is any warmer this year! ) from March through Christmas, the problem is one of adding ice to the reservoir in order to lower the temperature of the water in the reservoir. However, the same routine as outlined by Jerrold can be easily followed....lower the temperature in the reservoir to BELOW the desired temperature using ice, and then wait for the heater to bring the temperature UP to the correct temperature. The short time that it takes to develop film, and the large volume of water in the reservoir, assures one that the temperature will rarely increase much above a few tenths of a degree in the reservoir. Once the film is developed, a degree or two change in temperature in the reservoir is completely irrelevant because the slight increase of temperature in the stop, fixer, and wash are not significant for black and white processing. For E6 one might want to have some warm and cold water available to add to the wash as needed in order to temper the temperature fluctuations in the reservoir. I have not developed E6 film, and hence I will defer to Jerrold and others regarding E6 and maintaining temperatures in the bath. However, doesn't the CPP have an inflow valve that will draw water in from the tap in order to keep the temperature stable?
There simply isn't a better or more consistent way, IMO, to develop film-especially LF sheets.