Just curious as how you carry that spare 20 inch wheel. Is it too big to fit in the well the regular spare goes in under the bottom or do you just haul it in the truck bed?Not any help, but when I was in your shoes. I picked up an extra 20" Enkie wheel (hard to find). Now I have a matching spare and I rotate 5 tires.
Like you I was worried about being 1000 miles from home and having 3 good 20" tires 1 good 16" tire and one bad 20" tire