I used 4 3/4" pvc pipes with connectors. My goPro is anchored to the lower pole about 16" from the bottom. I just connect as many as I need to reach the bottom an stick into the bottom to stabilize it.
I took it one step further and added an antenna wire from the camera to my phone so it doubles as a underwater camera.
Here's the youtube link of my youngest pulling perch up:
https://youtu.be/SoyYyMKgb6g