Ok so I'm about ready to start the modding. I'm going to install some angle iron on top of the rear belly pan to make sure it makes the 15* cutoff and then move on to boat tail structure. Thinking of securing it inside the hatch and below the bumper to triangulate it out. I'll make some crossmembers between them for stiffening and then build off that triangular prism to apply the cardboard skin.
I also was reading Darin's boat tail prototype thread and how the car WITH the 4' boat tail was shorter than a Camry. I went on Wikipedia and found out I can go 36" back and still match the length of a regular cab SWB Ford F150 pickup. So I entered that length into Alias and modified the 3D model for a longer tail. I want to mount the license plate on the back of the tail, but realized quickly that making it 36" long would not give enough space for the plate! (and this tail is 13* all around) So it's probably around 32" long here. I think I'll try this. It should give no more than 2-3 square feet of wake which I think is pretty muf*ggin good.
Gotta pick up some trailer lights too. And research how to install them :P