3. Move production overseas (or at least to a different manufacturer), make changes to the design
Why would you have to change the design? Have you tried getting quotes yet, say on AliExpress? Is it not possible to find a manufacturer that wouldn't compromise the build quality?
If you revert back to the replaceable back panel, that would decrease the number of skus, and i'm sure you can find a manufacturer that would make a run of 200-250 full-spec cases for 180USD. Possibly, you can also have them shipped disassembled and unfinished, powdercoat them in the US, or just have them shipped finished but disassembled. Not sure if that would make the package smaller. Might have some issues with QC if shipping disassembled.
If you like or don't care to do it yourself, I can pester some companies and see what they say.
I believe that it's possible to move production overseas, and keep the quality the same, maybe adding 1-2 months to delivery, but still getting everything done by Christmas.
I don't know anything, just trying to help
Which other forums/subreddits should I post that review to?