Sous-Vide Chicken Thighs - Effect of temperature swings?
I think your temperature range is good.  155 to 160 is a good place for thighs.   You will need an hour to an hour and a half.  As long as you don't drop into the danger zone you will be fine.  You could just check a thigh with a probe thermometer at the end of an on-off session to see where the temp is.  Sounds like a bit of a pain, but certainly doable.  One caution...that looks like a small pot.  If you are doing more than one or two thighs, you will crowd the bag and might not achieve even cooking...this could create a danger if the center of the package did not reach 140.  Advice:  Get a circulator!  If you enjoy eggs, for example, the price is worth egg cookery alone, in my opinion. :-)

By the way, while many people prefer this route toward fried chicken, I actually have had the best success with, and prefer Keller's Ad Hoc recipe.