sounds like what you want is to be sitting more upright and less weight into your hands.

Once the steer tube is cut, that's it. But you can get a different kind of stem. Not necessarily a shorter one but with different angle. It can significantly raise the position of your handle bar and will do the same thing as a longer steer tube.

Having your hands going numb during a ride isn't safe. so ask your LBS for stems to raise the position of your handlebar. Also look at different style of handlebars. Some are more ergonomic than others. Winged bars (drop style) may give you more surface area for your hand to rest. They are not just for getting better aerodynamics. Again go ask a reputable LBS for their suggestion. Ask them, "I have issues with my hands going numb while riding..."

Hope this helps.