I'm trying to create a background for a traffic street scene, as seen from the pov of someone riding a motorbike.
To accomplish the visual perspective of moving through the street I thought it might work to draw blocks of houses, extrude them to 3D layers and rotating them 90 degrees so they would extend into the Z direction. Using one such series of 'house block layers' to the left and another to the right of the centre, plus another layer for the horizontal street surface would result in a 3D model of the street:

which I could then move as a whole to give the illusion of riding through the street.
My first attempt used just the 3D layers; but it turns out that extruding a 2D layer containing shapes stacked on top of other shapes - in this case, the windows and doors in the houses - results in z-fighting:

I tried to work around this by keeping a copy of the original 2D layer and putting it in front of the 3D layer by way of a facade:

which looked like that might work indeed. But when I rendered the animation of the whole street moving towards the camera some of the layers exhibit a kind of blinking or flickering, especially obvious at the top edge and in the distance:
(best visible in fullscreen)
I wonder what causes this? I first thought it might be related to the stroke width, for the rendering engine might have some trouble figuring out how deal with that. But I removed all the strokes at the left side of the street at one point and the problem persists.
Could it be that it is related to the 3D extrude settings? I've checked "materials" in the Edges section of the 3D Options tab of the Layer properties, and "extruded side colour" under the Shading section.
This is how I have organised the layers:

Does anyone know what is causing that flickering behaviour?
Or is there maybe an easier way to accomplish what I want?
(I've though about doing this scene in Blender, since that's specifically tailored to 3D - but if I can do it within AS that would be great.)
Any help / suggestion is much appreciated!
Anime Studio Pro 11.1 / OSX Yosemite 10.10.5