I love designing :)I just built a cargo/storage/dog area/sleeping area last week. It's made from 10" cedar boards for the supports and 1/2" plywood for the top. It is 4' long and 4'3" wide (coulda been another 1/2 or 3/4" to fit snugly). Just in front of that I made a speaker box that adds on another 11" of length to the deck area. All this (on top) is covered in "scrap" from Lowe's hardware ($25 for 5x24')This pretty well takes up most of the rear area...oh, and I took out the rear seats too to accomodate this cargo system...This kind of system allows stuff to be placed in containers underneath for easy access...as for airsoft guns and all that comes with them, I'd make something that looks like a mini-Tonneau cover with hydralic lifts or something. I'm in Search and Rescue and this area is for my K9 and I during searches or for transporting stuff and people.Also last week I Herculined the lower body panels and wired in Hella lamps for the front bumper. (pics to follow soon)Good luck on the project! It was 100 degrees during most of my work...hope your's is cooler!Dana