For best results build the plane so that the control rods are equal length to each elevator half. Here is a link to a reversing Y-Harness.
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXAFN1

As far as transporting in the back of a truck as you describe. I have a buddy that build a craddle out of 2x4's and carpet with J-hooks that he uses light weight bungi cords to restrain his planes.