I have a 3k ft grass runway I'd like to be able to land and takeoff from but the issue is it hasn't been maintained in years and about half of it is now too bumpy to land or take off on. The other half is fine, but at gross weight and high density altitude in the summer (8k+ feet) I need at least a few hundred more feet to safely take off without going on to the super bumpy part. The runway is otherwise in great shape other than the bumps on half of it. Tried driving a car over it at landing speeds and practically shook the car apart on the bumpy half. ;-) So, what would be the best way to smooth out the bumpy parts? Of note here is the ground is pretty rock hard. Like, even a 600 pound, four ft wide tractor pulled spoil aerator with giant sharp scoops almost doesn't penetrate at all. Just scratches the surface. Also of note, I have a 42HP tractor at my disposal. So what's best here?