The misconception is you need power, way more power than the shot calls for. What is true is you need to contact the c/b very low with accuracy. You really do not need near as much power as you think if your accurate.
As mentioned a 9 footer with new cloth is fairly easy. Bar boxes takes little effort. Table conditions and equipment dictate how much effort is needed no matter what size table.
Instead of thinking power up, just that thought is a stroke killer. It has jerk and slam written all over it. Think about a slow smooth take away and finish your back swing. That helps you start a smooth forward progression. When it starts smooth you get through the c/b with accuracy.
You'll need less power which increases accuracy, its a win win. Try it at more comfortable distances. You know how simple it is to draw table length from a foot away? At 4 feet its still simple. At 6 feet you need more speed but not anywhere near hard. Try that if you like, its easy to note when your using to much effort. You are right though, I'd still rather find a different route if available. Long distance draw shots are not as accurate. Sometimes yes and sometimes no.
Rod