If you set runs, slides, and crossovers, with emphasis on the runs and crossovers, you'll catch just about any otter that comes through there. Remember, they have a large territory, similar to a bobcat or coyote. It may take them 10-14 days or maybe more to make their loop.
I know of people that use rubber crawdads and things of that nature to help grab their attention, but nothing beats putting a trap where they're gonna be traveling to start out with.
The only thing that I can think of that will really improve your odds is to find a toilet and set that up. But like I said, its hard to beat a 330 in a run.