you can practice body position in every corner. not just turn 7. IMO, 7 is one of the least important turns on the track. maybe instead of worrying about that hairpin, you can work on body position in turn 1. its more of a sweaper and will allow you to actually stay in position while going thru the corner. 7 is just hard and late on the brakes, then early on the gas. turns like 1 and 10 are turns that will help you cut down your lap times. just try and stay relaxed with your arms and keep your head down low. stop by my pit (young blood racing) if you wanna go out for a couple laps.

when you slide off the seat, you wanna get about half way off. have the edge of the seat riding right about in the middle of your ass crack. like jim said, make sure your upper half is over as well or you will be crossed up, as so many new riders get. try the old saying of getting your head down like its in front of the side mirror (rather or not you actually have a mirror). and like spiderman also said, look through the turn. this will help the corner "slow down" and allow you to get on the gas sooner.