Questions about body types and practical styling

My next work event includes a panel with no lectern. The speakers will remain seated while taking questions. My full length mirror gives me only part of the picture. I have been reading about color and body type analysis while trying to understand how different style systems describe proportion. I would like to use the vocabulary to compare outfits without treating a category as a rule for every situation. The trouser line changes once I am in a chair. Comfort also matters because I need to concentrate on speaking. I can take a few seated photos before deciding. I would use the same distance and angle for each photograph. The event photographs may show us from the side as well as the front, so I want to consider both views before making a decision. How would you adapt silhouette advice to a seated event?