My solution has been to monitor the fermentation using a thermowell and a second controller (I happen to have a couple).
I place the chamber temp probe in a couple cups of water to help dampen temp changes. By monitoring the fermentor thermometer and adjusting the controller accordingly I can keep the fermentation temp within a half degree of target.
Trying to run the controller based on the fermentor temp didn't work well because to drop the fermentor temp even 1 degree requires the freezer to run a long time to change the temp of that mass...you end up with an ambient temp below freezing
Something is always fermenting....
"It's Bahl Hornin'"
Kegged: Sour Saison, Pale Ale, Aggie Ale, Firestone DBA, De Koninck Blonde
Bottled: Belgian Quad (Grand Reserve), Derangement (Belgian Dark Strong)
On Deck: Pliny the Younger