Petey:
Higher winds you want it centered. This equals less draft, more twist - less power.

Less winds you want it more towards the daggerboards, more draft less twist - more power.

In your case, I dont think you should have it any further aft than the daggerboards. Reason is you have plenty of body weight to hold the boat down. You want max power so ease the rotation almost all the way out.

The trick is to see a smooth entry point on the leeward side of the mainsail. You can see this by noticing the lee telltales make sure they are flowing straight back and up a bit. The windward tales would be close to stalled.