Looks good, but don't get too carried away with the aluminum right now. Keeping it bare was a great advantage for installing brake lines, fuel lines, electrical, pinion angle, driveshaft, etc.

I'd also advise that you don't fasten on the back wall until the trunk deck aluminum is installed. If you place that wall on there, you won't be able to reach the rivets for the trunk floor, and drilling the holes for the roll bar could be a little more difficult.

John Sitton did a good right up on his trunk expansion project found HERE

The pass through is easy to fabricate. It's just an aluminum wall set back about 8 inches from the back of the cabin. I cut mine out with a 6" hole saw on the ends, and a skill saw to finish the horizontals. I can come by sometime and you can check it out if you want. I don't use it as much as I thought I would.