Although a bracket sounds like a good idea I think that
1. you need lock nuts due to vibrations
2. You are not guaranteed that it will not swivel and it may
3. look a bit bulky when mounted
On the Falcon I've got I opted for an aerial on the starboard side of the console because of the very long distance between the A-frame and the console. Also in case of a damage or emergency repairs all is close and highly accessible. Finally, in the sea environment is a RULE
not to have too long wires and complicated connections.
In general you should keep everything simple to minimise any problems that they will arise anyway