I HAVE NEVER HAD ANY LUCK KEEPING MORE THAN ONE ROOSTER. I HAVE 50 + HENS I HAVE TO KEEP ONE ROSTER IN THE COOP AND THE OTHER OUT. I KEEP ONE PENNED UP WHEN I LET THE HENS OUT. IF NOT THEY WOULD SURLY FIGHT UNTIL ONE WAS DEAD.
I've had four roosters and around twenty hens and everyone got along well, but I think the key was they free ranged and just separated into their own little groups and got out of the other groups' sight. Space is crucial here. You'll just have to try it and see how things go, keep an eye on the hens for bare backs or stress behaviors (pecking, etc) and manage from there.
Yeah, people have been keeping multiple roosters with flocks for thousands of years. Occasionally there are serious problems but it usually works out. Some have already been mentioned but I think some critical things are breed, space, the personalities of the individuals involved (both hens and roosters), and whether they were raised together, either as siblings or as father-son.
I recommend you keep as few roosters as you can to meet your goals but there are no magic ratios involved. We all have our unique situations so we’ll get different results. I’ve had more problems with good ratios than with bad. Each flock has its own dynamics.
Then you should be fine. I'm assuming there are things to break line of sight, the land isn't all just flat pasture. I'd think your chances are great, but as always you just need to keep an eye on the birds and see how your individuals are doing in your circumstances.