I would not attach on top of the RPod. I made a mount for an amateur radio antenna that allows me to place the vertical antenna on the A frame of the trailer. I have a Stromberg-Carlsen Trailer Tray. My bracket allows me to set a PVC pipe on it and tie it to the front vertical brace of the trailer tray. The antenna is mounted on the PVC pipe. It would not be too difficult to do something similar for the cellular booster. I'll need to take and add a couple of pictures.

If you are using a directional antenna (which is needed in many situations) then a convenient way to rotate it slowly while checking signal strength is required. In my experience the pointing process takes more time during setup than making the connections and raising the pole.

I would put two clamps on to hold the pole in position and rotate it by releasing the bottom clamp slightly. Once in position then I'd add the third clamp.

Also Android phones have much better signal strength apps available than IOS in my experience.