I have adequate ground clearance with the 14x4 prop. I'm guessing it is about 2 inches. I could use more, but it has not been a problem so far.
I used a Hyde soft mount on my YS 63. With the soft mount I get some movement of the engine and I had to allow for this movement by cutting away the cowl.
I do get good cooling this way also, which I believe is very important on a plane that is intended for 3D flying. I'd rather have the cowl cut back and not look quite as good than burn up an engine by overheating it.

Jim