I will say a 7.0m sail.
That sail must handle easily 20-25 knots. In the PWA they will only use a 7.0m sail if the wind is gusting to 30knots.
I wont use it until it hits at least 22 knots. If youuse a 8.0m V8 you must be a big guy. because that sail is for light wind. i am sure your are pulling a lot of downhaul to flatten that sail and that is a problem because if the wind dies just a little that sail whont have any power at all like that.
I recommend a TR-5 or TR-6 from MauiSails.