i'm wondering why not use a double boiler, stovetop style?
seems to me, if u use a thermometer in the water of the outer boiler, get it to the exact temp u want with the flame regulated, it would stay that temp until the water evaporates. in which case, i would have another pot of water, preheated to replace whats evaporating

given the apparent fluctuations that exist in different crock pots and ovens in general, this is the method i plan on employing as soon as i have the nugs/keef to work with.

there's my nickel.