Have a single cab truck box with the following external demsions. 59.75" L x15"h x9.75"bottom x 5" top.  Box is devided. I would like to port the box a use two 10" alpine type r's.  Would like to do something like the decware truck box but need help figuring out port. Alpine recommends a 10"x1" port 20" long. But that is in a box that is 12" x 12" x 10.5" not a truck box. Any help would be greatly appriciated!