I've got a Kenwood something-or-another in the GT. When not in use it has a blank plate showing. It's pretty high tech when in use. The plate flips and reveals the face plate. CD player too!
I didn't buy it; it came with the car, but I do like it.
Personally, I've always felt like anything other than a portable boombox in a roadster was sort of like asking someone to slit the top with a box cutter.
I had a cheap am/fm cassette in my '79 years ago. Even then, I wouldn't lock the car. Sure enough, one night, someone stole the radio ( worth maybe 2.00 USD at Goodwill ). I wasn't happy about it, but on the other hand, at least, since I didn't lock the doors, I didn't have to shell out 400.00 ( 1995 dollars ) for a new top!