There're couple Gamba models with detachable triggers. Usually they command a premium maybe because people want this feature like Perazzis.
Gamba makes very high quality shotguns, the workmanship is really up there, but due to bad marketing skill and agency/ representatives issues, they were not popular in the U.S.
If you hold one in your hand, or take one apart, you'll see the quality. Parts are available in Italy, if you can't find it here, Marcello on this site can get you what you need.