I feel like there's one final piece to the Dick Whitman puzzle we still haven't seen or heard yet.
Now that we know what Uncle Mac's was like, I really
doubt that Dick stuck around any longer than he had to. I think he would've moved out the first chance he got, probably in his late-teens. He dropped out of high school, so he must've been working early on.
He was 24 when he went to Korea in 1950 and he was clearly a rookie soldier.
There's a gap from 1942/1944-1950 that's completely unaccounted for. There had to be some sort of spark that made Don decide, "I have to get out of here!" "Here" meaning Pennsylvania. Coal Country. Not necessarily Uncle Mac's.