Ron, you don't need forearms like Popeye if you let time do most of the work. In all fairness, I've never kneaded 8 batches at once, but I have done 6 17" pies worth, and I can't recall that being the slightest bit taxing (with plenty of rests). I chose 8 because, I think, any larger than that and you'd have trouble getting a big enough bowl.
I minored in ceramics in college, so I have developed pretty strong arms from the countless hours kneading clay, but if you use good technique and knead with the weight of your body, rather than just your arms, it doesn't take a great deal of strength.
I'm not anti-mixer, just anti KA. If you want to start shopping for a used Hobart or save up for a bosch universal mixer, then, by all means, I think those could make your life easier, but using the KA for 2 pizza batches of dough... I wouldn't do it.