One advantage of going to a normal airfoil section toward the tip is a thicker aileron. On some of the original wings, the ailerons got sorta thin out there and were prone to flutter. Several tricks were used to keep the flutter under control but most of these became unnecessary with additional aileron strength.
Keep a bit of washout in the wing and don't go too think on the airfoil section on the tip and you should have an enjoyable plane. If it were mine, I'd probably stay with a 10% to 12% section out there. This is common for many aerobatic designs these days.
One of the original full scale planes, Cosmic Wind #5 is on display at the EAA Museum in Oshkosh if you ever get up that way.