Update after ~10 months, (about 6 or 7 months of driving, car was stored for 3 months)
The 3M 5200 coating is still firmly in place wherever I had coated the boots. Not easy to see in pics, but there is some new minor surface cracking in areas that I did not get at.
One outer boot has a small leak at the narrow end. Looks like it is leaking under the clamped end. Wondering if I could just tighten the clamp? What with? Maybe nail puller pincer/pliers plus vicegrip? Or remove the clamp and put on a tie-wrap or gear clamp? But how to remove without damaging boot?
(click on pics for full size)
Here are typical boot pics taken today:
For now, other than fix clamp, I think my boots will last for a while yet!