I am in the same boat. I donate blood every 10 weeks, which is the maximum my local blood center allows. My Hematocrit is always around 50, which is definitely high and potentially dangerous for risk of stroke. Lowering your testosterone replacement therapy (TRT) regimen might lower your hemotocrit over time, but it could take 6 months plus and you will then possibly suffer from low T again.
P.S. Hematocrit is basically showing RBC content, though a few other things factor into total hematocrit.
P.S.S. There is a common drug that can lower RBC content, such as used in Polycythemia patients, called hydroxyurea, but its a rather unpleasant drug.
P.S.S.S. You can also take a baby aspirin a day to lower blood clot risk with high hematocrit (lowers stroke risk)