Done it a bunch. As long as the base is at least 3 inches long it should be fine. Very sharp knife, slice right down the middle then put it where it won't be bothered by clowns or anything else. The mouth wil reform with 10 days or so and you want to feed it like crazy as soon as it can eat!
They heal amazingly quickly. Just don't do it on the smaller guys <6" when expanded, they have a tough time.