There is an alternative antenna placement. If you have a rain sensor (located at the rearview mirror base), you can route the antenna up the A pillar, across via the inside edge of the ceiling/windscreen and simply pop the antenna pad into the sensor housing. No drilling, disassembly/reassembly etc needed. Simple, really - you just need something to wedge the cable at the ceiling edge.
You can then cap the hole for the old antenna.
You can then cap the hole for the old antenna.