Ok, so after a while, and some conversations with some folks in the second life blender community, I solved this one. Two problems contributed
The first was some hidden geometry. My first model didn’t unwrap well, so I made an new collection and rebuilt the pallet with simpler topology. I hid the old mesh using the eyeball icon in the outliner.
This only hides the mesh IN THE VIEWPORT. So, when I baked, the render engine saw both meshes, some on the UV map, some not. Sometimes the visible faces caught the light, sometimes they were hidden by invisible faces. Hence the weird patchwork of black faces on the bake.
I fixed this by simply selecting the old mesh and moving it off to the side.
Second thing is baking saves a new image IN MEMORY but the image texture node reads the image saved ON DISK. So I’d bake a new image, but immediately connect the baked texture node up to the output, and see the same thing I’d seen at the beginning. I finally noticed that little asterisk next to the *image in the UV editor, and saved the fixed baked image, and everything was wonderful.
Anyway, hope this helps someone