I am widening and lengthening a Ford F1 truck. For the doors I drilled aluminum rulers #40 drill for clecos. That way I could match drill the door and slide the pieces 6" apart and re-attach 4 rulers. Stack and clamp the rulers together and drill them all at once on drill press.
For the cab sectioning I used 4 large turnbuckles and welded the ends to temp braces. Very easy to just move a few thousands. Drilled #40 holes in the body and use this trammel bar to check that everything moved exactly the same. Much more accurate than a tape measure. Can draw a line between holes before cutting to make measurement is still in alignment after moving the pieces apart using flexible ruler for curved surfaces.