It may very well be legal to have a gun on the north property, but you said it is where jr. high and high school have their youth group activities, which to me implies it is a school function. I agree with Joe that is is probably not off limits all the time, but more than likely during those school functions
Youth groups in church(at least this church) have nothing to do with schools. No more so than a group of kids getting together at McDonalds, Dairy Queen or any other place. Church youth groups DO NOT meet the definition of school in the Indiana Code.
As far as were to park? If you have a gun in the car, park over at Wright's Gymnastics or park on the street on the south side of the campus. Shortly it won't make any difference anyway....