Prop rooster tail problem

Hello all:
I have a 82 Supra Star, 350,1:1 Tranny, Had a 14x12x1 prop stock prop and someone suggested a 13x12 for this problem and have same problem and it's even harder and it didn't help.. The wake is flat but I have a hard rooster tail in the middle 6 to 10 inches high between 18 and 22 off at 31 mph. It will take your ski out from under you if your not paying attention skiing 22 off. I never really paid attention to it because I've always free skied at 15 off. The rooster tail is at 15 off at 31 and 32mph. Your thoughts or suggestions on a fix will be greatly appreciated.
Thank you