I would recommend using a phone stand. This is the one I have:

http://www.amazon.com/dp/B08D6KM95D

It works like a tripod but much more compact. It goes from fully closed to open and set up in a few seconds and takes up very little space. It works great and weighs practically nothing. It can also be used as a selfie stick.

The pole/pipe camera clamp that I use came with a construction laser I own and can't be bought separately. But if I had to buy another, I would get these things:

http://www.amazon.com/dp/B00YGEVBQI http://www.amazon.com/dp/B072KNBV21 http://www.amazon.com/dp/B06ZYKXYQK

You need all three because the pole clamp is designed for a GoPro so you need an adapter and phone mount to use it with your phone. I have that phone mount and I like it a lot better than the one that comes with the phone stand. The screw clamp on it is much easier to use than the spring clamps that most phone mounts have.

The nice thing about the pole mount is that you can also mount it to the pole you're on, for an overhead shot.

I don't have any experience with suction cup mounts so I can't offer any recommendations there.