I finally resolved this by increasing memory. I followed: Self-managed cluster - Deploy which creates a t2.micro service on AWS. After finally figuring out my problem was OOM. I resized to a t3.large and that allowed my schema to POST.
The documentation should make mention in this section that this creates a 1Gb instance and is eligible for the free tier but does not meet the recommended 8Gb of memory. And that a t*.large is recommended. I think that would clear a lot of confusion up for new users running docker images on their own aws instances.
I was just looking for a way that maybe didn’t use as much memory to create the schema. That may not be possible though.
My schema right now is 40Kb consisting of 110 types, ~1,000 predicates, 250 @search directives, 267 @hasInverse directive.