Dear all,
I returned yesterday from the annual Wikimedia Conference in Berlin.
I've quite a few things to tell you about the conf and the strategy, but let me start with this: thanks to Leon Ziemba and Sam Walton,
we have a nice way to show book-based statistics, meaning the aggregated pageviews for an entire book (main namespace + all the subpages).

Here's the important diff:
https://it.wikisource.org/w/index.php?title=MediaWiki%3AHistlegend&type=revision&diff=1878676&oldid=1699217

So, as an admin, go into your Mediawiki:Histlegend page, and add this code

{{#ifeq:{{NAMESPACENUMBER}}|0|'''ยท''' [https://tools.wmflabs.org/massviews?project={{SERVERNAME}}&source=subpages&target=http:{{urlencode:{{fullurl:{{ROOTPAGENAME}}}}}} book pageviews counter]}}

Then, go into the History of a random ns0 book: you should see a new link "book pageviews counter" (translate as you wish).

I hope this tool is useful!

Aubrey