Hi Lorenzo,
Try the Exocet Windsup 11 8 it's a great board for what you want.
I used to windsurf race boards, speed, slalom and wave. I got the Windsup when young family and had local beach with offshore wind, could sail 2 to 300m to get to the wind line and its planes and gybes well and I've done 27knots.
Take the front foot straps off and smaller fin then grab your paddle and leash for sup