By "plate" I thought you were referring to some kind of antenna mounting plate. License plate never entered my mind, even though you mentioned "hamsters" ...... and I'm even a hamster myself! Duh ....
Hi, I'm new too Welcome !! I have used several types of CB antennas on prior Sprinter based rigs, !. Glass mounted (window over bunk) 2. Magnetic mount to front cowling area. 3. Metal bracket attached to under hood bolt.
All those worked ok depending on antenna base type, and eliminated any drilling into the body..most antennas work best with a metal ground.
NVBanjofan welcome to the forum. FYI: It is usually a waste of electrons posting a response to a thread that is almost a year and a half old. Did you not get a warning notice?