For what it is worth, I looked into the "flip-flop trunk" idea. I do not think that it is a clever name and I hate flip-flops, but it might do the job.
First, I sometimes forget that people in this forum usually write better than those outside. I developed a headache deciphering bad English.
I only saw one kit, this is the place that sells it the cheapest:
Flip Flop Trunk Conversion Kit . They bad-mouth other kits, but I did not see any! I found comments about people thinking that it looked cool until they saw how it worked, and then everyone allegedly shouted "rice."
Sure...
Here are instructions for doing this with little cost. I think that the only real cost is of a few washers:
How to: Flip-flop trunk - SRT Forums - SRT4, SRT6, SRT8, SRT10 & Dodge Forum
I read comments on both techniques that the edge near the rear window did not seal afterward, which would definitely be a problem.
This would certainly require a modification were one to do this and build a Kammback, hatch, or whatever. The weight and distribution thereof would be very different.