I've always heard those were absolutely horrible for your feet, even if you have regular, non-flat feet.

I won't disagree with ya there. I'd never wear them.

Another update:
My arches are blistering like crazy (which is an issue I've had for as long as I've been running). I'm using runners tape and still having the problem.
Like I mentioned earlier, I'm just using a neutral shoe that I tighten up like crazy instead of finding a shoe that actually fits, despite trying on a ton of name brand shoes, including in narrow sizes.
Does anyone have any suggestions? Maybe a lesser known brand?

Went to Fleet Feet last week. My left foot is a tad longer than my right. I tend to get black toe nails on that foot when hiking. I wear a 15. They tell me I need a 16 2E. They don't have any of those!

Yeah, Fleet Feet's selection sucks.
Unfortunately, they didn't work for me, but Luke's Locker may have your size.