If you want to avoid suppression then avoid all that might cause it. Including rad.
Proviron might not suppress that much but don't take my word for it. Don't remember much of it other that it's basically DHT and sometimes also used in PCT.
Blocking DHT conversion while using DHT based PH will definitely reduce gains.
Not to 0. Still useful.
If you have bad side effect from DHT (hair loss, acne, prostate problems) then taking something against it might be wise but wiser still would be to stay away from DHT based PHs.