I love the night troll for walters. All alone in the darkness, nice and quiet on the water.
There's a river that I fish a few times a year, and the only time I can seem to get a walter bite is a night. We don't leave camp till around 9, and return at 12ish.
There's current there, and lots of ups and downs, so I'm not sure the exact depth they hit at. Somewhere between 5 and 15 feet. Trolling wally-divers, or rattle traps.