Thanks, Lyman, it had to be something like that.
FWIW it's common practice on racing cars to muck around with Gurney flaps to trim the rear-end grip. For a long time I couldn't get enough front-end grip on my racer but did some work on the nose and gradually got more and more out of it. The rear wing originally had a small Gurney on it but I took it off to improve the balance with the low-downforce nose. The Gurney was about 8 mm tall.
The final nose configuration I came up with had enough downforce that I had to refit the Gurney to the rear wing, extend the slots on the wing mounts to get more AoA, and also add some wind deflectors under the tail to try to control the airflow a bit better.
Made about 1.8 G's lateral at low speed, about 2.3 G's at high speed.