Something that just occurred to me while I was looking through kids' books for a rather younger aim: have you test-read the Great Brain books, by John D. Fitzgerald and illustrated by Mercer Mayer? They're based on the author's real childhood around the turn of the century in the American West, and are full of capers and adventures. A couple might be 'too scary,' as I recall the boys getting lost in a cave once and so on, but YMMV. Or AMMV, as the case may be. :->