Saison fermenting

I have a hennepin clone fermented with cultured yeast from a hennepin bottle currently being force carbed in a keg. I am without a temperature controlled fermentation chamber (read: to lazy to build one) so it fermented at ~64-70F. I'd like to do another batch using the same recipe and yeast, but ferment in the attic to get some warmer temps so that I can compare the taste. The attic has been getting to ~85-88F during the day, but it drops back down at night. Is a ~20F degree fluctuation between day and night going to be a problem for the yeast? Will this temperature change shock the yeast at all?

I would think that might be a problem, maybe you could wait till it warms up and the insulate it with a couple blankets/sleeping bags, or hit it with a space heater or heat pad/blanket at night? Not sure.