It does not take much of an opening to provide all the air required. Fuselages are generally not vacuums unless they can hold pressure, positive or negative. I can't think of any wood framed models that fit that description. A small scoop on the side of the fuselage could work well in minimizing any potential diaphragm pressure issues and provide a little better balance with the induction system if you chose to install one.

So no, you don't have to have a scoop but it might work out a little better for tuning if you did.