A mounting apparatus includes a fixed mounting structure that includes a first fixed fitting including a plurality of first flanges and a second fixed fitting. A rotatable mounting structure has a swivel fitting configured to engage and swivel with respect to the first fixed fitting. The swivel fitting includes a plurality of second flanges, one of which is configured to rest on one of the plurality of first flanges when the swivel fitting and first fixed fitting are engaged. The rotatable mounting structure also has a slide fitting configured to slide with respect to the second fixed fitting based on the swivel fitting being engaged with the first fixed fitting. An adjustment assembly is arranged at an interface between the second fixed fitting and the slide fitting. The adjustment assembly is configured to adjust an angular position of the slide fitting relative to the swivel fitting.