Saxman, a dorsal fin, such as the type fitted to later models of the Mustang and Thunderbolt, would probably have alleviated the instability problem...at least to some extent.
The main problem with the F2G-1 was that, while the R-4360 produced abundant horsepower, the Corsair design was entering the area of diminishing returns. While the F4U-4 could produce speeds approaching 440 mph, the F2G-1 with 700 more horsepower bested that figure by little more than 15 mph. So, it was hardly worth the effort involved.
In any case, the advent of jet powered aircraft rendered further developement of such piston-engined fighters irrelevant.
Regards, Shuckins