You can raise both ailerons very slightly which will allow you to reach a higher angle of attack without stalling the tips. But this is risky business and may provide only marginal results. Another drawback is that it will create tip stalls when you go to negative G's.

By the way, stall strips are designed to cause the inboard part of the wing to stall first. FAA regulations require an artificial stall warning to be installed if the natural stall warning of the wing is not severe enough or early enough to meet certification requirements. This is normally done electronically or mechanically. The manufacturer does not want to sacrifice lift by aerodynamically creating a pre-stall warning. I know, because I've flown hundreds of full scale test flights in dozens of types of aircraft from sailplanes to Boeing transport category aircraft.
Hope this helps.