The Cross-section view tool is one of the best additions that makes looking at internal facets a lot easier. It would also be nice to have the option to remove hidden facets from the facet select list so you don’t have to click select through lots of hidden facets to get to the one you want. This would be a great time saver.
The cross section view is rendered by hardware (simply anything in front of a plane is invisible), whereas the feature you request would need a manual calculation to identify facets that are fully in front of the plane. This is a good idea though and I’ll note it on the wishlist.