Best way to compost Datura stramonium in situ?

After planting walnut trees, watering, then mulching with wood chips from an arborist, my 100' x 30' berm or hugel is covered in Datura stramonium (jimson weed, thorn apple, devil's trumpet...). The plant has died back following the killing frost leaving an excessive quantity of Datura leaves, vines, roots and seed capsules.
To remedy the problem, I am considering spending the winter months gathering nearby dirt (by digging a dry pond for water infiltration) then using the subsoil from that depression to cover the billions of seeds. After depositing this subsoil (caliche) over the plant remains, I plan cover the "dirt" with cardboard, followed by horse manure, branches, leaves and and other sheet composting material. By spring, I'd like to cover the sheet compost with local sacaton grass.
Anyone have better organic approach to get Datura stramonium under control without hauling it "away"?

Amy, your plan I think will work if you can place enough material on the berm.  The only thing I would suggest is to remove all or most of the seed pods as there could still be seeds inside.  Keep a close watch next spring for any new plants bursting forth and dig em out!

The datura in the east produces a lot of seed but I don't remember a very high germination rate.  Please keep us posted on how your plan works out.

Peace