Haw! In Mexico, I saw a leaf spring on a truck replaced with a properly shaped tree branch!
You are almost there, take one torsion bar out, after propping it open with tree branch Mopar part no 2765375.
Note which direction twisting is being applied, the angle at rest, and anchor one end in a vise or other manner.
Apply torque sufficient to change the resting angle more, or less, as desired, for more or less torque when installed.
Then selectively try combinations of hi-mid-low positioning, (both sides) to perfectly balance the weight of the deck lid.