You can do a +2 extension with an 18" barrel without sticking out past the end of the barrel.
Look at a Nordic or Mesa Tactical barrel clamp. They cost more, but they offer a small rail that works well for mounting your light out front and to the side.
Side saddles are a personal thing. I like them on HD shotguns, but I'm finding that I don't much care for them on "fighting" shotguns. Get a cheap TacStar one to try out. If you like it, good. If not, you're only out $20.
Look at a Nordic or Mesa Tactical barrel clamp. They cost more, but they offer a small rail that works well for mounting your light out front and to the side.
Side saddles are a personal thing. I like them on HD shotguns, but I'm finding that I don't much care for them on "fighting" shotguns. Get a cheap TacStar one to try out. If you like it, good. If not, you're only out $20.