Obviously I am not as long as you (holy shit)...but at 8 inches in length I still find some positions difficult such as doggie-style....with a woman who has not only a healthy butt but also thick thighs. There is practically a 4-inch gap between the surface of her ass and actually hitting pink.
Her on top is much better, but even then if she has big thighs, it can again prove to be difficult to penetrate her completely.
Now that I think of it...the more "cushion" she has surrounding the vagina, the tougher it will be to get balls-deep.
Not every big girl is a size queen, but most I have met typically are. Perhaps if it didn't take 9 inches of dick to achieve 3 inches of penetration then they may change their minds
I love women of all sizes and thats God's honest truth...but I find it easier to have sex with leaner women.
OmahaBeef