So I'm still kind of playing with this prefatory to releasing a very long blog post on it.
Turns out the include worked fine once I set the System Includes in Preferences. It didn't do anything in this case, but it doesn't kill the renderer. One less thing to comment out.

The global_settings were fine. The
Code:
ambient_light rgb <0,0,0>
bit simply made everything dark. The first way to fix this is to set the rgb vector for ambient_light to <1,1,1>. The other way, which is a bit more flexible, is to move the position of the light to <0,0,0>. For a light_source, the position vector is the first vector in the block. You'll find if you render as-is, without altering the light type, you'll get a nice day/night map of your world. Cool, but if what you want is a simple map of the entire surface, it pays to comment out the parallel and point_at lines. Upping the color rgb vector will also make the map nice and bright. I prefer the ambient, because it's difficult to find the proper value for the color rgb vector and ambient tends to make the map look less... "muddy."

After doing this several times, I find I can readily get it done in less than 15 minutes. You know, if I'm not spending hours documenting each step and puzzling out what the next step should be.