Yes, do not cut sections through nodes. For your plate model, I cut a section through the plates at elevation 109 inches which is 1 inch above the nodes at the 9 ft elevation. I compared the Total Force for the plates at that cut section to the Surface forces at 9 ft. The FXY and MZ are the main forces of interest and the values seem to be close as seen from the screenshot below. There would a some difference due to the fact that the cut section for the plate is at elevation of 109 inches whereas the surface forces are at elevation of 108 inches and there is some loss of accuracy closer to the nodes.
