I am going to sound like a grumpy old bastard but.....
Sue - you need more downhaul
Sue - you need more downhaul
Sue - you need more downhaul
Sue - you need more downhaul
Sue - you need more downhaul
Sue - you need more downhaul
Sue - you need more downhaul
Sue - you need more downhaul
When you work on one thing at a time you will find solutions.............get the rig feeling light and then you can concentrate on other aspects clearly
As i previously posted - when I cranked more on (60mm people - no wonder it was pulling on your front hand) it was a light wind setting for me at 85 kgs - thanks Mineral for reminding me of the weight difference - we could have given it more to get a good setting for you in those conditions.
I was sailing a 10m / 125l /56 fin combo in the same conditions - I dont want to post to have a debate - but rigged right that board sail fin was a reasonable combo for the 10-15knots flat water that we had.
Ideally you come in crank another 10mm downhaul on test / crank / test / crank / feel happy about a setting / change fins / test yada yada yada.
Its a subjective process.
No amount of posting on Seabreeze will rig it correctly.
But a good starting point for you is MORE DOWNHAUL and work on one thing at a time
Always happy to help you downhaul on the beach - just get some longer rope