The navigation cube has the preset views "T" (top), "L" (left), and "F" (front).

Having the additional views (bottom), (right), and (rear) would be of major help when adding supports manually.

If this feature already exists, please tell me how to use it.

The easiest way to implement this feature would be to modify cube clicks with the "ALT" key.

When holding down the "ALT" key and clicking "T" on the cube, you get the "bottom" view.

When holding down the "ALT" key and clicking "L" on the cube, you get the "right" view.

When holding down the "ALT" key and clicking "F" on the cube, you get the "rear" view.

A more difficult, but better, solution would be to emulate the navigation cube in Autodesk Fusion 360.

Thanks