The problem with me and shorts is:
The only khaki shorts I really see are:
a) the pleated soccer-mom "knee length" shorts
b) the super-short cut-off "hollister type" shorts which I would assume are not appropriate for rush
nice jeans, a knee length skirt etc are preferable to khaki shorts... even a khaki skirt is better (although I don't have one of those either)
at my school the "recommended" dress code was:
day 1: jeans w/ a provided t-shirt when I rushed, jeans w/ a white t-shirt last year
day 2: nice jeans or khakis with a nice shirt
day 3: dress pants/somewhat dressy skirt etc
prefs: dress/skirt ("what you'd wear to temple or church" but no evening gowns or anything)
I wore nice jeans on day 2 since I feel more comfortable in them than khakis