Mojo,
Have you guys tried the half round weights at all? With the full round weights... it didn’t leave much that you could add in the way of cubes before being over weighted on the rear bumper. Maybe you guys were just pushing the envelope too far and that is why you got the wiggles? Since I don’t have a track to tune on... I usually go fairly conservative with my weighting strategy... using the room left over back there to try to taper the rear bumper for better aero. It seems to me that having extra trunk space is a nice problem to have. These days I am gradually starting to get more aggressive with my weighting strategy... but still think that anything more than around 2.3g behind the axles is sorta pushing it.
I tried half weight with mixed results... and they weren't as fast as my full swaying car.
If I cut back to 2.3g behind the axles, I wouldn't even bother with a weight pocket back there.