After 6 hours of SSH struggles, 3 of which were unnecessary and my own fault, Backblaze upload is finally working.
Believe me, I am much much more excited than the dull title implies.
(This means I will probably post more in the future.)
Also, I hate Ghost. When I first installed it, it had the "best minimalist writing blog" roadmap. Over a year later, it's transformed into some abominable monetized newsletter platform. While I'm quite happy with the minimalism, I was expecting improved blogging experience, not a shocking swerve over to making subscription money.
I think I'll stick with Ghost, because it works, and I really don't want to attempt another blogging platform installation. And as for the downsides that will probably never get improved, I'll live with it.
I just found out now that Ghost arbitrarily limits file uploads to only the basic images. No pdf, zip, or any other filetypes allowed. Lame. A few Github issues popped up wanting expanded file types, and the responses by the devs amounted to "lol pound sand."
Obligatory celebratory image: