Since I don't have a truck, the following idea came to me- why not build the horn pieces in take-apart form? Build the sides with raised battens (3/4 by 3/4) all around the slope part and bottom piece, to form a "raised dado", build the horn slope normally, to fit into the dadoes (no glue), with 2by4 bracing on the slope piece, (no back), then use 2by2 spreader pieces across the front top and back top. Use allthread to pull everything tight. Now the whole horn box comes apart for transport as flat sheets, then can be assembled
on site. I can easilly put all that stuff on top of the Jeep, and put the woofer boxes and Mid horns inside the car.

Any thoughts??

-Larry