I can manage two Roos with my 10 girls but they are australorp and really laid back. Any more than that and they seem to fight. The only exception is when I had to separate one for bumblefoot. As soon as I put him back the other guy beat him up.
I free-range quite a bit and rely upon roosters to reduce loss of juvenile chickens to hawks. My chickens are full-sized with many being game chickens. Silkies are a different story. They should be confined with every protection measure possible. They have limited ability to see and have a large number of mutations making them extremely vulnerable to predators of all colors. Particulars of male silkies I am not familiar with although they might be adaptable to bachelor pen keeping. If not, then pen excess males singly. Otherwise re-home or eat them.