If your wheels are breaking traction, then you definitely would make things worse with a more powerful engine.

I have to believe that low rolling resistance tires, perhaps inflated to a high pressure, with a narrow profile are at the root of this problem.

Driving uphill in 'B' mode will do nothing but aggravate you further.

I have noticed a very carefully programmed 'creep' when I release the brake. whether I am on flat terrain, or going uphill from a stop the electric motors are driven in such a way that the car moves forward at about the same rate.

Did you try just staying off the gas and let the electric torque pull you? I wonder if bringing the ICE online too soon or too aggressively compounded the problem.

How about your Traction Control/VDIM? Was it on and working? Even when I occasionally lose traction in water the car never lets me lose control.

Here is another idea.... MOVE! I left the midwest in 1986... between December and April, I won't even go back to visit