Get a honking big mower to cut away the worst of it. Burn it, haul it off, or (my usual, environmental solution) mulch it.
Then rent a honking big tiller and plow it under.
When (with luck, if) it germinates, plow it under again.
Get a truckload of green wood chips - not mulch, you want the green stuff. Spread it all around and choke the weeds.
When the woodchips turn to mulch, you're ready to do whatever you want.
A bit unorthodox, but worked for me a couple of times. YMMV, and a lot easier than pulling by hand.