Why roundpole fences? I always use stakewall for boar pens, so that the boars can't see through the fence (and it's stronger than roundpole, too). This pen is inside another stakewalled area, sometimes with a moat as an extra defense.

Crops don't panic or need to be tamed so I use roundpole for them. They are also inside the bigger stakewalled (and moated) area, of course.

Never had boars or crops destroyed by raids. The worst that has ever happened is a troll breaking a single gate in the outer stakewall.