Yep, that is the base I used for the antenna I used externally.
I just contact cement velcro to the bottom of the mag mount antenna and to the shelf, and no need to drop the shelf. (we also have put on several wire ties to hold cables, a terminal block and radio/tuner mounts on the shelf without dropping it--just use a very short screwdriver or right angle screwdriver. We use a right angle drill, with a very short bit for starting the hole for a screw on the shelf.
Either way--the satellite radio is a real winner!