Those do look like a small caliber gun dents to me - i.e. a .22. The metal is stretched to almost breaking through. You 'allude' to a loggers caulked boots - possibly an evening of drink and lust on a weekend, the truck wouldn't start and a previous owner was just trying to 'kill' it.
Now, pick up cab corner repairs - that's a tried and proven method using glass, newspapers and Bondo and comes with a 10 - 10 warranty ( ten minutes or ten miles, whichever comes first )