Yes, they do fight through the fence. They seem * more likely to fight through a fence than in the open together. But it's easy to line the fence with tin panels or shade cloth or any number of things. I've gotten several rolls of 6'x50' shade cloth on Amazon for $50. It goes a long way. They also have 4' and 5' tall rolls, I attach it with zip ties to the fence.
That said-Silkie roosters are way less likely to fence fight than other breeds. I've had better luck with multiple Silkies living together than most other breeds. So there's a good chance it would be a non-issue and even if it became a problem later you could line the fence 24" up with something to block their view. It doesn't have to be any taller than 2'.
@MrsDickey Are these the ones you're deciding on keeping? Or asking about gender?
Rabbit math is an interesting idea....who'd of thought??

I'm in love with one of the little ones my husband brought home, she's super calm and cuddly like my Holland Lop.
I'm deciding on where to take them for spaying and neutering. Neutering is no more than a cat neuter but spaying is anywhere from $100-$200 each. I've banded lots of livestock but I won't be one of the people banding my own bunny boys. If one of you all try it be sure to let us know how it goes.