What I did was add the bbpress shortcode into a page then I set the page to use the full width template.
This is the default bbpress forum.
https://ronangelo.com/forum/asteroid-theme/
This is the page that I use for the forum. The same link on the menu.
https://ronangelo.com/asteroid-theme-forum/
bbpress Shortcode
[bbp-single-forum id=xxxx]replace the xxxx with the forum id
You can add this on the Custom CSS option to add the lines between the topics.
#bbpress-forums .bbp-body .topic {
border-top: 1px solid #BBB !important;
}