Assuming the stall warner is adjusted correctly, it should NOT go off anytime during the base turn or the turn onto final.
You are anyway descending so unless it is a calm day there will be some wind shear, so if you are say 8kt above Vs then you can lose that margin in a flash.
There is no point in flying that slowly. The time you want to nail your final approach speed is on the short final, not on the base leg.