By visually, I assume you mean in 3D (vs just cutting a section through the mezzanine and dimensioning a line at your local code-specific head clearance height?
Many are not aware (writing for others as well as you - perhaps you are) that the Zone tool creates a 3d volume that can be visualized and scheduled. Displaying a translucent zone (by default, zones are disabled in the 3D filter) can visualize that you're asking for. You can set the zone height to be your code-specific head clearance and create it on your mezzanine...and crop the top to the overhead elements.
A better visualization - showing only the acceptable head-height areas - can be accomplished by using a Morph as a 'helper' to get the exact line(s) at which the head height becomes acceptable. This 'trick' is due to the fact that the Morph tool displays itself properly as a projection in the 2D window.
So, create a Morph mass of the desired minimum head height by tracing / magic wanding etc the mezzanine in 2D ... then in 3D, pull/extrude it to the desired height and then trim it to the overhead elements. The lines of intersection will then be visible in 2D and 3D ... swappable only in 3D. Use those lines to create the desired zone for the mezzanine at max height, trimming for visualization. Hide the morph layer. The result will be visible in 3D (and schedulable) as the usable volume.