This is a beautiful solution.
To clarify for those who might not understand immediately (took me a second):
- go to your theme folder
- choose the layout you want bbpress to use (full page, # of columns, etc. — whatever options your theme has)
- copy the the corresponding .php file
- name it “bbpress.php” in the very same theme folder
- simply refresh the page and bbpress will now lay out the way you want it to.
Perfect.