You are correct about the aero effect, I have been considering just removing the antenna completely for that reason, drop a bit of weight off the top as well.
Now that I know it is only a radio antenna I will likely do so and fill it with some silicone then cover with some vinyl wrap.
I do not want to drop the headliner when I run a cable for a rear view camera, which I must have for safety reasons, I might be able to tie into the antenna cable, have to see what it is, then less work and weight instead of running a complete new cable.
I really do get where you are on the power mods, it was where I was going to stay when I bought the car but I am such a long term modaholic I did not stick to that very well but it would of been a smart move for sure.
Attention to detail, taking weight off, cleaning up the airflow, they do add up and often times do not cost much, something I have done for decades, even more when it was all I could afford to do.
Thanks, very much appreciated