I still get admonished to keep my back straight when I get down low turning in on someone who is much shorter than I am. I've come to the conclusion that a physiological peculiarity is to blame for this. When I was younger, I had to give up barbell squats and do seated leg presses instead because I couldn't help but lean forward to keep my balance with the barbell, and I suffered a serious back injury as a result.
The problem seems to be lack of forward flexibility in the ankles. If there was more flexibility there, I'd be able to get my knees more out over my toes when squatting down, thus shifting my center of gravity forward a little more and allowing me to keep my back straight and maintain my balance during the squat. As it is now, when I try to squat down keeping my back straight, I feel as if I'm going to tip over backwards--and that would certainly make me more vulnerable to counters.
So are there any general uke-loading tips for judoka who can't help but hunch forward like some kind of simian when they squat down?