If it's moved closer, it looks and feels wrong, plus the fact that either side will not line up with the windows anymore if you do so.
Bounding box? You high again?

It would be better to move the C-shaped block of railings farther to the left and set their collision model to "Use bounding box", as it would achieve the same effect and not be detrimental to optimization at all.

To prevent people from cutting/passing eachother in line as the props leave a bigger open space inbetween them (collision wise) than expected.