It's the tren itself that causes hairloss - not a DHT related metabolite, so unfortunately 5AR blockers will have little / no effect on tren related hairloss.I'm not sure of the mechanism at which tren causes hair loss, but if it could be blocked by finasteride/dutasteride then I'd throw that in too.
Staying away from DHT derivatives is a good rule of thumb, with the exception of Var, which is a DHT derivative, but very mild on the hairline.