I know you said no drupal, but I would still use it for this particular job. It has a core (not third party) module called "book" so you can be sure it will always be supported in whatever current version there is without the module update headache.
It comes packaged with a "block" that lets you show a sort of table of contents for the current book when someone is on a page of that book. So the layout in terms of getting that to show is pretty straightforward.
It also makes it fairly simple to put Next/Prev navigation at the bottom of the page.
If you set it up so that books automatically get added to a given menu, that should be pretty much automatic too.
For the images, you'll probably want something like img_assist or some other third-party module, which does pose the problem that you mention, though of course you can always put images in by hand (i.e. FTP to a /images dir and then just add an <img> tag).
I've never used it for 80 pages, but I use it a lot for things that spread over 5-10 pages. For 80 pages, you might want a two-level hierarchy so that your TOC isn't overly long.