@mmorris I would seriously reconsider; our HOA has been battling cattails for over 30 years around a 4 acre pond and where they once were 20' thick, 3/4 the way around the pond, they are now limited (I laugh when I say this) to a stretch of about 100', about 8' thick. And this is with trying to kill them with a chemical every year. You don't really want to do this, imo, unless you can contain the roots and annually double check to see that none have slipped their shackles. If I were going to do this insane thing, I'd put the tubers in large plastic 'mortar pans'. Approx 3' x 2' x 8" deep, and heavy duty plastic. But seriously, there HAS to be another tall marginal you can fall in love with, isn't there???
Going to have to add you to my prayer list, if you continue down this path to Hel....