If it's truly a 7 meter day, it would be perfect for your board you chose...ANY board capable of carrying a 7 sail.
Be it 92 liter slalom, 100 wide Formula, 72 wide freeride, or foil of any size.
Now if you really meant 12-17 mph wind, that is more specific and precise.
A slalom racer might use a 7 meter sail in 20-28 mph wind.
A expert free foiler would choose a 7 meter sail for 4-8 mph breeze.