Here's a photo of the Rope Man Ascender. It fits in the palm of your hand, weighs almost nothing. So simple to use, your 4 year old could do it. Also very very cheap when the cost is compared to the purchase of a wheelchair.

http://www.campmor.com/webapp/wcs/st...berId=12500226

You simply clip your full-body harness to the ascender, which is attached to the rope, climb up and hunt. You will never worry about hitting the ground again.