The rods are a good fit on the sled. Looking from the bottom side, there is no spacing visible. I could have shortened the rods, but that’s pretty definitive. With some washer of different thickness, I tried to determine the extra distance and ‘measured’ 2 mm.
I 3D-printed a filling layer, mounted it. A good fit with no material stress and parallel rods.
Linear Rod Support Fill v1.f3d (50.1 KB)
Linear Rod Support Fill v1.step (23.9 KB)
Linear Rod Support Fill v1.stl (37.0 KB)