What year model is your Wife's GO 200.
How wide is it?
We used to put 70 cm Formula Fins in the back of the '02 and '03 100 cm wide Start boards, and with a big enough sail,
they absolutely flew in light air.
The '02 with the more square stern was the favorite, but the '03 with the rounder tail was close to as good.
Planned about the same windspeed as the 100.5 cm wide Formula boards, but were a whole lot easier
Just took a bit more effort/technique to get them going vs the Formula.
A big fin is your 2nd best friend to get planning early.
First you need the board width, they you need the big fin to go with the board width, then you need the big
sail to grab all the wind you can.