Keep in mind, that the depth of the average female is roughly 6-7" (no, I dont remember where I read that). If your unit is longer than that, all you accomplish is pounding the hell out of your date's cervix, which is neither comfortable or enjoyable for her!
As long as you are close to average length (5'-6"), you should be more concerned with GIRTH since that is what she really feels while you are doing your thing. The bowling ball trick isnt going to help that problem.
Finally, isnt the real issue stamina? Other than the "9 short, 1 long" technique I havent heard any solutions that enable a good solid 5 minutes of hard, fast screwing.