You can use a pvc flange on either side of the enclosure, cutting a notch out of the flange on one side so the perch can be removed. Then you just need to drill a hole through the flange and perch to stick in a bolt to stop the perch rotating on the snake. Should work well for pvc or wood if you can match the diameter of the flange and perch. You could also just make a frame with the perches attached and remove the whole frame from the enclosure when needed.
I look for branch's , usualy fork shaped , that fit neatly in such a way they don't need securing. Just be careful to make sure its safe for the snake and nothing can fall , trap or injure it while climbing around when your not there.