B-Squared,
It's hard to see, but yes I made sure there is room for air to circulate (I made the hole about an 1/16-1/8'' all around to make sure. Plus it's all still open in the fuselage, so I don't think it will be a problem.
I will start with the recommended size of 24x10, and then I think I will experiment with a 4 blade to see how it does. So far on the bench with a 24x10 it pulls VERY strong, so yes, it will sound awesome and go like stink! Can't wait for summer!