touralie, time to get down in size. But progressively, do not get down too much. Something like 8'6" x 30/31 x 130L could be great.
As jb1979 said, foot positioning is key. Try to move your rear foot backwards and closer to the rail(*). And let time for the board to dig the rail before moving your body weight inside the turn.
In my experience, what makes a board easy to put on a rail depends on the wave speed:
- In slow waves (15s mandates narrow boards.
- in medium waves, lowering the rail volume helps as much as reducing width
- the faster the wave, the more the width becomes critical. >15s mandates narrow boards.
Smaller fins and hull shapes (V, concaves) help, but it is marginal.
(*) This vid may help: