Enormous wind turbine blade transported over stone arch bridge - GIF

[Frank S]

I cant see the point of having the trailer so long? Why dont they retract the telescopic trailer, and move the sliding rear support backwards? The overall length of the trailer becomes shorter, the blade is still supported at the same distance and its easier to manouver.

There are afew reasons why not to do what you asked.
1 is the shorter the trailer the longer and wider arc of the tail swing while it may be more maneuverable in some places the additional out swing of the end of the blade means it would be easier to strike obstructions.
2 this has to deal with the maximum allowable rear overhang that can be permitted by law to transport.
Another thing that does not apply with the blades is the distribution of load centers but would when hauling the tower tubes. then thye would most probably slide the mounting trunion much further back.