You gotta remember too is that as the plane rotates forward the prop comes closer to the ground. I would measure for what you need for the size of prop you are going to use. A good rule of thumb is 20-25% of your wingspan should be prop for a good STOL plane, more to the 25%. Then you need to consider the terrain you are taking off and landing from, is it grass or a paved parking lot? How good of a pilot are you at take offs and landings? Would you tend to nose over a lot? How many props do you have on hand to replace your broken ones?
For me cuz its a bush plane, just for authenticity I would like to get as much clearance as possible and still be functional. That being said, I am no expert at take offs and landings, busted many props attempting both, and tend to take off from grass. That means I would be looking for a couple of inches of prop clearance as the plane sits level.
But that's just me