This is not the correct tower for a pop-up camper. You will need to use Yakima Control Towers and install either Yakima tracks or Yakima fixed mounting points (landing pads). The Yakima tracks use Yakima Landing Pad 1. Your choice of fixed mounting point really depends on what works with your configuration.
Another option is to install Yakima Widebody brackets on the side to simulate raingutters. Then, instead of Q Towers or Control Towers, you would use the 1A Raingutter towers. There are tall versions available (spacers, etc.) if you have a unique situation requiring you to mount the brackets lower than preferred.
Either way, your pop-up camper must offer a stable and secure bolting surface, lest your rack tear/shear completely off during a sudden deceleration or turn.