SOLIDWORKS 2018 now allows you to hide faces temporarily when adding mates. This helps to make selections of faces and edges that are not visible. Previously we would need to rotate components or use Select Other for the non-visible selections.
When in the Mate tool, use the Alt key when hovering over faces to hide. You can keep using the Alt key to hide additional faces. This is temporary until you make your selection, then all faces will be visible again.
If you keep your cursor over a hidden face, you can press Shift+Alt and it will show the face again. Also holding Ctrl+Shift+Alt will show a preview of hidden faces that can be selected to be shown again.
See the functionality in action in the video below (at the 0:25 second mark):
The functionality is very similar to how you can quickly hide and show bodies and components using the Tab key. See our blog posts to see this functionality that was introduced in SOLIDWORKS 2016.