I think I'm on my way - what you see here is an entire evening's work. The first few blocks are always the hardest. I did some ripping because one dark green was incongruent with the rest, and distracted from the light/green contrast.
Here's the back. I think I have all the seams going the right direction. I found I need to use one needle setting for the more complex blocks, and a different setting for the simpler alternate blocks - which I'll do last.
Ironically, I made up one "simple" block, only to realize I should have used light green. Oh well, that's what I get for calling it simple. :)