Skip trucks are 3m wide apparently.
More like 2.55m. Anything in addition to that will be the mirrors, which are foldable.
With the gates, when you make them, it is good to make them slightly out of square (say 10-20mm on the diagonal) so they are a fraction high at the middle. That way, as they drop, they get better before they get worse. Similarly. if you are worried about sag, a wire rope and turnbuckle from top hinge to bottom outside can help a lot.