In the North Country for citabria's that is common. Be careful not to shrink it too much, take your time. I agree with shrink up on the inside with possible less affect on paint on out side. Remember some large hair dryer's can get very hot. While you are in there look around and at the small diameter horizontal cross over tube just in front of the tail post and structure where the forward tail spring bolt goes through. Corrosion on these aircraft very often happens at this location first and the lower longerons second.
Good Luck, Brian