I did the same, and the RV-10 vent works great on the right hand side in this location. The only scary thing is cutting/trimming the side skin, donít want to mess that up!
Originally Posted by rv7charlie
My purchased -4 had no vent for the back seat. I bought an RV-10 vent kit from Van's, which contains the stamped parts for two swing-out vents. Very reasonable price, IIRC. Each vent is ~ 2 1/2 x 1 1/2 inches, plus the perimeter mount. I mounted one on the right side of the fuselage, as high as I could under the top longeron and a few inches aft of the structure under the roll bar. It seems to supply adequate air to the backseater, and doesn't blow in their face, which helps avoid breaking intercom squelch when you have inexperienced passengers.
Very simple to install, very light weight, and I gave the spare to a neighbor for one of his planes.