I agree that 47 is not a worry, not high enough to mandate phlebotomy,
i get symptomatic around 53, really feel it at 54, but I don't think though that waiting for symptoms to develop is a good plan. I try to keep it below 52, but my own case is messed up, complicated by things other than TRT. If my erythrocytosis was solely due to TRT I'd prefer to keep it below 50, and lower my testosterone dosage if possible to try to actually treat the cause, not just do phlebotomies as stopgap treatment of high HCT.
Also, in terms of donating blood, if you are able, and feeling altruistic, please do! I am alive because of transfusions, and the generosity of those who donate. Heartfelt thanks to all who do!