yeesh, trying to lift 4000# of wobbly 'decks' is really, really asking for trouble.
2 tons as a concentrated block secured to the loader is 'ok' but big wide 'decks' just says 'LOOK OUT' !!
I'm wondering if these 'decks' are 10 x 40 in size next to trailers ? A picture may help let us think of possible SAFE rigging options for you.