> I'm still kind of amazed how difficult it is to create a Lisp program that isn't hundreds of MB in size.

That's not true IME. No doubt SBCL binaries are large, but they start around 70 Mb and grow from there. The growth depends partly on how many shared libraries are loaded when the image is created. Commercial Lisps are supposed to be better, but I haven't used them so I can't really say.

For smaller tasks SBCL (and possibly others) support scripting using a "shebang line" of "#!/usr/bin/sbcl --script".