You can put all your workholding devices (vice, clamps, etc.) and toolholder into your CAM software and it will find some crashes during simulations.

Most CAM will do good simulations.

I usually run a new program without an actual cutter in the spindle. Then I run it with the cutter but 2-3" above the actual material to be cut.

Many people will do trial runs on machinable wax.