Tony --
Take a look at the hand bars at the top of the windshield sticking out from the front hoop on a Top Fuel dragster.
When we made our new set-up on our street roadster, we still had quite a hole in the tonneau, but nothing to grab hold of. The steering wheel's under the tonneau. My knees are bent to about a 60º included angle and you can apply a lot of pressure without anything happening. 'bout the only thing you can grab hold of is the windshield -- and that ain't good.
Reminds me of the first days of Disneyland in the 50's -- they had an annimated Lincoln who got up from the chair to talk to you. He had his hands on his knees. Try it yourself. Put your hands straight out to your knees, don't bend your elbows, and try to get up. Good luck.
Stan Back