The ladder appear when GSX calculates the marshaller will end up below your field of view, depending from the eyepoint height in the cockpit and the parking size.
So yes, you MIGHT be able to customize this, by raising the "Max Marshaller distance" parameter. However, it might result in the marshaller being placed inside a building, depending on the scenery of course.
GSX doesn't have any knowledge of the actual shape of the buildings so, it cannot possibly know if at a certain place the marshaller could be placed farther away without being inside a building.
