Welp, I just picked them up today after a second round of stretching, and I think they're going to be ok. In addition to the stretch, my shoe guy put a little slippy (silicone?) spray along the inside back of the boot where my heel slides in—that was the biggest problem area.
You're right about the fit being wide, though. My heel definitely moves around a bit once my feet are in, but it's nothing too bad, and I think I might indeed opt for some insoles after hearing y'all talk about having helpful results with them.
I guess the thing I still find so bewildering is that I'm a pretty skinny guy and have found these boots to be downright impossible at times to get on—I've given up on several occasions and just put on another pair. Why were they especially tough those particular days—maybe too much salt the night before? Haha I don't know. All I know is that my feet are pretty normal if not narrow width, average volume (this was a new term to me until I bought some hiking boots recently), and it's been a mega struggle. For anyone who had slightly heftier feet and/or ankles: forget about it. And that's just kinda nuts for a pair of boots that cost so much... would someone even be able to return them? I guess there'd have to be a way?
Regardless, psyched mine have finally been at least somewhat tamed. Thanks a ton for everyone's help!