OK, here's where I am on this as of Friday 7/27.
On Monday I cut open the last section of harness and found nothing wrong in any of the wiring.
I taped the harness back up and reassembled the truck to a point that the engine could be started and run.
With a NEW ignition switch in place, I ran the engine for 45 minutes at 1,500 RPM with a volt meter connected across the battery. System voltage remained at 14.3 to 14.1 the entire time.
Never blew the fuse.
Just to make sure that the new ignition switch had "cured" the problem, I then put the old ignition switch back in and ran the engine at 1,500 for more than an hour and it never blew a fuse! !@%^^&$%#@!&%$#!@#* !! And the old switch never got hot or even warm. I took the old switch off and once again measured the resistance and it still shows around 9.3 Ohm.
But not wanting to give this old switch any benefit of doubt, I consigned it to my toolbox (for future reference and possible use in a DIFFERENT truck to see if that truck blows a fuse) and put the new switch back in.
So I am unable to prove anything about what was taking place at the beginning but I can't stop wondering if the initial finding of the wiring harness pinched between that bolt head and the steel hydraulic pipe might have somehow resulted in current sort of "bleeding" through the thinned out insulation and heating up the fuse after a few minutes of operation.
The final test was done on Friday by putting the truck back together completely and letting shop personnel use it (instead of our designated shop lift) do normal tasks.
Truck ran in intermittent duty for about 5 hours with several different operators and the fuse has not blown yet.
Before I drove the truck back to the dock to release it to service I personally drove it across some rather rough areas of pavement to kinda simulate the conditions of entering and exiting trailers that are mismatched to the dock plates.
It did not blow a fuse.
Time will tell if there is still a problem.
If it blows the fuse again I will revisit this thread with that story.