Hi, JBDad!
Do you know the Ralph Fletcher (
www.ralphfletcher.com) books on writing for children? (I mean the books are for children who are writing, not adults writing books for children! I'll go back and reread the chapters on clarity!!!) We have them, and though we haven't used them much yet, I've read them a few times, just because they're so lovely--he's very respectful of children's desire to write, and offers a lot of practical advice to young writers--he really takes them seriously. I expect that there would be many ideas there that you could toss around with your little guy.
There are four books (Live Writing, The Writer's Notebook, Poetry Matters, and How Writers Work), and I love them all!
peace
minnie