Eric brings up a good point. You descent speed will be dependent on how easily your rocket can be damaged on landing.
Also, it may depend on the winds in your recovery area. You may want a smaller parachute so that your rocket isn't damaged AFTER landing. I have seen rockets pulled along the ground by large parachutes.
In engineering, there is rarely a perfect answer that solves all your problems. You have to choose an answer that meets all your requirements as best as possible.
What do you want to measure with your proposed wind tunnel? A wind tunnel seems like a lot of work to collect data that may be collected with easier and less expensive methods.