Closing the loop.
I used a prescription test-c bottle without issue.
I transferred all the test to a new sterile bottle, then repeatably “rinsed”the test bottle with alcohol until no oil was visible in the alcohol. Then a few bac water rinses. Then I added the reconstituted peptide. It remained clear with no degradation and I used it all week without event. Not a lab-level process, but everything was new, and I kept my process as clean as possible. My big concern wasn’t injecting non-sterile chems, but compromising the peptide via cross contamination.