You certainly don't need to stir the mash. It will convert and extract just fine without stirring, and taking the top off to stir is going to contribute to losing mash temp.
First off, doughing in at 170 is too hot. Assuming about 10lbs of grain at room temp, you should be doughing in closer to about 164 to normalize the mash around 155. At a 170 dough in, you are mashing closer to 160-161, leading to more complex sugars in your mash that the yeast can't break down, which leads to more malty body and residual sweetness in your final product.
Then, you could keep monitoring the temp and adding heat, but that's a PITA in my opinion.
Get an old blanket, sleeping pad, or moving pad or go get one at goodwill. Here in the FL summer, I can maintain temp within one degree just covering the top with a blanket. In the FL winter, I wrap the entire pot using two blankets (one around the top and bottom, one around the sides, with a bungee holding it all together) to keep temp within one degree. Your weather may vary, but you get the idea.
THEN, do a 170F, 10 minute mashout, and stir like a maniac during the mashout. This 10 minutes of stirring is far more efficient and valuable than stirring during the mash.
I get 76-78% efficiency with these steps and a good fine crush.
Good luck!
