Hi
I have a Starboard Isonic 147L from 2018 that is a Ultra Lightwind board.
I used it 3 years with a 8.5 camber sail and had some fun but only after 14 knots breaze kicked in.
So i stoped using it for fin and no using it for foil so i can go out with 10 knots with a 7.8 with much less pumping to get going and doesnt stop in the lulls.
I recommend you buying a Lightwind board that has a box that handles a foil so you can use both fin and foil.
Foil has opened a lot of staying on the beach or hard days of pumping to fun days on the water :)