My wife and I have been sailing in The Gorge since year 2000 and this is the first year we had to skip because of COVID-19 (Border closed).
Too bad for me, I specifically bought the FW75 2020 for high wind Gorge days. However, my wife and I did get to try it in conditions very similar to the Gorge (St Laurence River, Québec City) and we are convinced that it will make a great Gorge board.
In our opinion, the ideal sail range on the FW75 is probably between 3.7 and 4.7. You can probably stretch if down to 3.0, but my wife (your weight) will jump on her Fanatic TriWave 69 as soon as it is 3.7 and under conditions.
Last year, it was a very windy Gorge (specially in June), so my wife used her 69L 60% of the times, the rest being mostly on the 75 (FW 2010) and a bit on the 86 (FW 2017). But on average over the years, 75L is surely the board she uses the most.
I am pretty convinced that the FW75 2020 is perfect for you for most Gorge days, but if you want to take advantage of those nuking days at The Hatchery, the addition of a smaller board is a must.
But if you want to keep it simple with one board only, an alternative for you would be the Grip 75, that allows you to use quad fins, adding more control for those really windy days.
What I would suggest is to have a talk with Eddy Patricelli at Big Winds, I am sure he will give you the best advice.
Guy and Sylvie.