Paul,
When is the last time you wrote an article and submitted it to the "big" guys? I thought I saw an ad in New Pioneer. Sure enough, a full page Permies ad. Why not write an article using information from your book and referencing the book in the article? People reading the article could then buy the book to gain more information. I can come up with at least 5 magazines off the top of my head that fit the niche. What about some of the outside the US magazines?