Limit navigation to pages in custom menu

Hi, thank you for a great plugin, it is much needed.

However, I’m wondering is there a way to limit page navigation to only pages listed in custom menu?

Example, I have a section on site called “handbook” which is basically 50+ pages sorted in custom menu. Menu is displayed as usual in sidebar but pages are quite long and navigation on the bottom of the page is much needed.
Right now, prev/next pages navigation also includes pages like About, Contact and Homepage which is, in this case, not desirable.

Also, I second requests in previous support posts like the one on
– http://wordpress.org/support/topic/linking-to-proper-pages-in-the-tree

I understand this is probably too specific but am willing to sponsor coding of this functionality.

Thanks

https://wordpress.org/plugins/next-page-not-next-post/