: Would joining 2 2 x 4 x 10' boards for a night heron strongback (13' 11"
: I believe) be realistic or effective? If so how should one go about this,
: I'd appreciate your comments.

As Rhed suggests, i would my 2 cents toward the same idea, 2x4s are too unstable for this kind of job,i`ve made a box beam , it`s hanging in the garage, didn`t use it so far, but i can see that it`s still straight after a few months ,hanging.

good luck