I use disposable vacuum bags made from 4 mil plastic and inexpensive caulking. Commercial versions also work fine. I just got started this way because plastic tarps and caulking are available locally.

Lay out a piece of plastic about 18" wider than the shucks and about twice the length.

Lay a piece of rope on the side of the shucks. Lay the vacuum tube in place and tape both the rope and vacuum tube down so they don't slide around.

Apply 2 beads of caulking around the outside of the shucks. Apply some extra caulking over the vacuum tube so that parts seal.