I'm trying to create a workaround since there is no current way of modeling a fence. (if you try to create a fence around a backyard it acts like it is a closed object and adds a roof.) So one thought was to create a new road style that looks like a fence. Issue is that we can create a Median that has height and width similar to a fence but when we apply the materials to the three sides, inner surface, outer surface and top surface it appears to use the TOP and inner but treats the outer as transparent. So when you drop this into the model what you get is a fence that looks lke a fence on one side but on the other it is transparent so you see right through it.
I've attached a 3D modeled fence (no material to deal with) Then i also attached the settings i used. This seems to work pretty well. Hope this helps