I have seen failed chassis components, and although main structures are unlikely to fail, be careful of your mount stiffness and strength. I personally had very porous welds on our steering column mount that resulted in a fatigue failure (luckily held together on track, and got repaired).don't worry chassis will stand all loads , i think it never happened failure in chassis during any competition (anyone correct me if i'm wrong)
There are also some pictures on Pat's corner of failed frames, I even think there are a few main structure failures.