I checked the dome light bulb and it was good. I checked the wiring diagram and found the common elements. The fuse was the easiest thing to check and appeared to be good. But, when I put a test light across the fuse, I noticed that the cargo light switch lit up. What's more, it stayed on with the test light disconnected.
Huh?
I am assuming there was some corrosion between the fuse contacts and the fuse. I removed the fuse and cleaned it and the contacts. I decided to clean all the fuses and contacts and discovered an SFE-14 fuse in the lower, right position - The one marked "Emerg & Stop" in this Fordification image:

The image shows a 20 amp fuse in that position and I suspect it should be an AGX-20 fuse because the owner's manual shows one for the "Emergency Warning System" - Sorta sounds like a NORAD designation doesn't it?
I'm guessing an AGX-20 wasn't available at some point in the past so an SFE-14 was substituted because it was the highest rated SFE fuse that was "short" enough to fit.
What size/type fuse is in the lower, right position of your fuse panel?