We only want one general board so don't need the "forum" and "category" headings.
I already figured out that page_footer() actually prints the page using display() from twig.php which calls display() from enviroment.php (there are 12 functions called "display") which calls display_with_assets() from environment.php which calls 4 other functions, each of which seem to reference several parts of the object hierarchy.
At this point I decided that it was best to ask where the relevant code is or if there is a simpler way.
p.s.: please direct me to the correct forum for this question if this isn't it.