As explained many times on the forum, we have to flag all parkings as GS, in order to get rid of FSX default vehicles, because we have our custom ones.
But, in any case, this doesn't mean that GA planes will park there, because the most important rule is the parking size so, a GA plane will always go to the *smalles* parking spot that can accept its wingspan so, before they'll start parking there, they will first fill all smaller GA parking spots.
