Jack, it would be interesting to know more about the scale of the project; how big is the model and what flight envelope are you aiming at?
I assume the data are to be recorded or telemetered; quite a challenge for a home-brew project given the small size, weight and dynamic pressures involved. Yes, a lightweight vane is the way to go. Assuming the model is prop-powered, it really ought to be on a boom to reduce errors.