Tony - This may not be applicable to your GRMS car and it's intended use BUT ----
Flailing my GTs around mountain roads, I have noticed that the rear tends to hold better if the tire pressure is lower in the rear than the front, especially if the car only has me onboard. I assume this to be due to the extra leaf in the rear spring which supposedly provides additional carrying capacity for the GT model. The point is - the rear springs are already too stiff for your purposes, especially since you have lightened the beast.
I think you are on the right track by removing leaves. I wouldn't worry about taking out another if I were you. Besides, you have lots of time to put it back in after you have road tested it, right?