I think that what you are asking for is nearly impossible. If you start tight, the kart tends to get tighter. If the front tires are struggling for grip, struggling to be the dominant axle right off the bat, its hard for the front to overcome the grip in the rear. Maybe you can find a sweet spot with the rear pressures where it will lose grip and the front will come back? From my experience, that is hard to do. If the back starts out as the dominant end, it will only drive the kart more as the run goes on.