I used a mag mount near the rear of the roof for a few months. I ran the wire in through the grommet used for the rear washer fluid hose. I did need to cut a small notch in the grommet to make space for the antenna wire. I puled the back hatch weather strip loose to feed the wire in and around to the rear seat area, where I have the radio installed. I have a PDF file that goes through everything, including the radio head installation, if members are interested. I did end up installing a permanent antenna above the rear dome light using a 3/4 inch hole and MNO mount.
Rick - WA8UMT