> Rural America is emptying out.
Rural America, in the sense that the OP meant it - "It is just a lot of physical work and being in the sun" - effectively no longer exists. "Rural America" is largely a term used by people who live in cities for people who don't live in cities, but the latter are by and large not "rural" by historical standards.
If you fly over the midwest, what you will see in terms of land use is a large amount of farmland broken up by enormous neighborhood networks and mid-size cities. People who live here are largely not working on farms. They are commuting to office jobs, service work, or gig economy positions. They don't walk anywhere, so they're not "in the sun"; even getting to the grocery store or a friend who lives nearby is practically untenable without a car. They certainly aren't living off the land. "Rural" America is basically the leftovers of farmland, and in many locations it's actively being partitioned into subdivisions.
I lived more than half my life to this point in a "rural" area, but for me this meant ~5 unfarmable acres. Virtually everyone else I knew lived in a neighborhood (isolated from other neighborhoods by miles of driving). This lifestyle isn't the idyllic thing it's made out to be.
> Religious fundamentalism, racism, homophobia, and outright Nazism
I don't think I'd point to rural areas specifically as the source of this problem. Instead, I'd point to the "Orange-County-ification" of the US. The heat centers for the problems you're talking about are relatively wealthy subdivisions full of people who can afford F150s that they don't need and keep small arsenals in their basements. Think people like the McCloskeys in suburban St. Louis: https://www.bbc.com/news/world-us-canada-53481537
As for racism - part of the truth of the "crime problem" in cities is the fact that huge segments of their populations are effectively a permanent underclass living in poverty or near-poverty.