The distance between your two images, or separation is in the view_customer.lua and is -7 for the left and 7 for the right - maybe someone will play around with this parameters?
But separation just makes the 3d effect / deepness and should be match your IPD
The size of the objects is related to the fov (just found the standard fov of the planes, no general setting (f-5 is 80°, maybe just for 2d?!))
Please Correct me if I'm wrong