Essentially, make a wooden frame or however you do it to include the drop down to the trunk. On the upper/top portion, use a heavy gauge metal grating... (I've seen it it about 1/8" round holes throughout the entire thing) Then cover the whole thing w/ carpet. It looks factory, but allows the air to escape. My only concerns or thoughts are that the carpet would hold back the heat. It's worth a shot to take your current design (which I like btw) and stick a temp probe somewhere underneath it, and make the one I've described and do the same. Keep up the good work!
