Flexing may miss it. Most likely to hit when both fronts hit and compress at the same time.
The 2" is over stock bump stops if you just add a truss with no other suspension changes. .
If you lift and install tall tires, they may hit before before the axle, but ideally you want the bump stops to prevent tires and anything from hitting. Every lift and tire install should include new bump stop chrck and adjustment as necessary.