Drop a P16 mast? Maybe you should think about another sport! That's a pretty light mast. No diamonds to get in the way. Just push that little stick up or lay it down in the rack. You'd really have to screw up to drop it on your car.
Now, a SuperCat mast, that is one BAD BOY! My SC17 mast is about 70 pounds with stays and trap lines. It's embarrassing to wear my truss at the beach.