Screw 3" × 2" uprights to the arris rails of the closeboard fence (preferably through all 3). First use a couple of bits of feather edge in the reverse direction to the existing ones to get them square to the fence, then screw through the lot. Add a bit of 3" x 2" to square up the uprights above the existing fence to allow you to centralize the trellis. Privacy trellis with a tighter pattern than normal trellis is your friend!
Screw 3" × 2" uprights to the arris rails of the closeboard fence (preferably through all 3). First use a couple of bits of feather edge in the reverse direction to the existing ones to get them square to the fence, then screw through the lot. Add a bit of 3" x 2" to square up the uprights above the existing fence to allow you to centralize the trellis. Privacy trellis with a tighter pattern than normal trellis is your friend!