You wrote "Writing a technical book is a profoundly uneconomic project." I think this is true if you go with traditional publishers. My last book, self-published and available for free to DSC members, also 100 pages, is better, more original, and more useful than whatever Wiley publishes on this topic (of course this is my biased opinion.) It also took less than 30 hours to write, and while being free, the benefit it generates is far above zero.