ncbi.nlm.nih.gov/pubmed/9168075
So while Tamoxifen may have an anti-estrogenic effect initially, that may change with continued use and actually promote the aromatization to E1 and E2.
For anyone on TRT one potential way to work around may be Primobolan injections instead of regular Test-E or Prop injections, since Primobolan cannot convert to Estrogen.
Other thoughts welcome!