Your remark that "My dad went to his grave saying almost nothing about [the war]" reminded me of encounters with combat vets when I was a Navy air traffic controller. When I joined in June 1974, America's role in the Vietnam War had formally ended 18 months earlier. Us youngsters were embarking on Cold War-era service - no combat. (As a woman, of course, I was prohibited from even serving aboard a warship.)
Some of my senior petty officers, however, had sailed with the Tonkin Gulf Yacht Club. Others had accompanied Marines into the bush as forward air controllers. They never discussed their experiences with us kids. However, I got a taste of what they experienced during a midwatch in the ATC radar room at Naval Air Station Brunswick, Maine (an ASW base which flew P-3 Orion sub-hunters; it's since been decommissioned). It's 1AM, nothin's on TV. So the chief and a couple first class petty officers started yarning about the old days. Another young sailor and I just listened. They went on for about an hour, trading harrowing stories in an oh-so-matter-of-fact way. When they finished, my shipmate and I needed a minute to resume breathing normally.
Anyway, SK, you did a four-oh job of writing this story. Give yourself a "well done." Next time I have a couple fingers of Old Tub, I'll toast you and your dad.