Hi,
regarding the question of "is this supported?" I would reach out to Adobe support.
In terms of general feasibility: It seems that your DR strategy relies on re-building the AEM instance(s) in a different region but re-using the same (original) S3 bucket via S3 multi-region access. This should work, and also from an AEM perspective it should be seamless (maybe higher latencies), assuming the existing S3 driver (shipped with AEM) supports that feature. And that's a question only the Adobe support can answer.