Can't help for the small cubby, As far as the ham radio mount, I have done this with both Yaesu and Icom radios where the head separates. A small bracket that allows up and down movement is attached to a block of walnut that has felt around it. It is wedged in the larger cubby below the smaller one. As @Mutant138 said to another poster, drill a hole in the back for the separation cables for a clean install. I still need to do that on mine. However, remove the plastic unit before drilling so that you don't accidentally rip into a wire headed for something else.

Thought I had a picture but will post that later if you wish. This is my second 5th Gen and I did the same to the first one.

For antenna mounts, I used mag mounts last time around but this time I went fancy and used a Rago hood mount which is "Fantastic". Love that mount. It was a bit tricky to find the right LMO base but once I got it, it is incredible!

Cheers, Bob