Fretless RDs were readily available from Gibson - if you asked for it. I've seen at least three, but they're hard to get.
If I'm not mistaken, then starting with the Ripper you could get nearly every long scale Gibson fretless from the factory though the option wasn't called often. I own a factory-fretless Ripper, a fretless Grabber, a factory-fretless Victory, a factory-fretless Q-90, a factory-fretless Les Paul DeLuxe, a factory-fretless Les Paul DeLuxe doublecut/Junior prototype, a factory-fretless Super 400 acoustic bass, a fretless Money bass and a factory-fretless Epi EB-1 reissue. I've seen factory-fretless TBirds, RDs and even 80ies Explorers.
Plus a fretless P-Bass, but don't tell anyone that!