Good post.
People think that the Amish have an living day to day habits that would be more aligned with how a "post-apocalyptic"/SHTF scenario, but overlook the materialistic logistics for their current living. As you mentioned, they use petroleum for farming, China labour for their clothes and modern (metallurgy) machinery for equipment and materials for their facilities.
If you remove the computers, synthetic fertilizers (some Amish even use this too apparently) and pesticides from a regular farmer (two things you already should consider to be less dependent on), your average ranch/farm land owner is on pair with the Amish. Only exception could be the community part that could be an uphill battle for less-religous demographics.
The more I look into this Amish thing, the only advantage I see them having compared to others is their closed community. That's about it.