1. Burn waist harnes and your short harness lines
2. Mast track on center position for tight course, -1cm for 120-130 deg
3. Foot straps outboard and in the back positions.
4. Seat harness, long lines & boom up should help clew drag. Also RSR may have been downhauled too much, add heaps of track strap to stabilise draft.
Isonic tends to have a bit of a floaty front foot, however above mods will help.
Have fun!