I agree with ChickenHouse, getting a Ram ball-mount added to your panel is the best, and had that on my previous aircraft.
However I've currently using Ram claw mounts, and have used them on a few other aircraft, and they are almost as good as having a fixed mount.
Small Tough-Claw? with 1" Rubber Ball
You can use them on the yoke, but despite the looks they don't need piece of round tubing to attach to.
They work fine on any suitable bit of aircraft structure, such as the coaming.
I also use the X-Grip mount when just using my phone.
X-Grip® Universal Smart Phone & Sat Nav Holder with ...