I notice you have removed the rear ariel. I left my base in position and used a sharks fin style booster. Cut away most of the shark's fin leaving the base and amplifier. It has a single wire with a loop, this is simply screwed onto the base using the hole that the ariel screws into. Very surprised that I get excellent radio reception and all totally hidden.
How are you getting on? I suspect as you have had it a few days that it must almost be ready for paint