I just took out my back seat and left it that way in my 83. Looked like ****, but I didn't add 4 times the weight in wood over what the seats themselves weighed.
I have taken the rear seat out of my 87 gt conv. and really you dont need a template. Because of the metal frame that surrounds the convertible top motor you can basically carpet the entire thing and it will look fine. When i took my rear out it only weighed about 6-7 pounds, really nothing to it, and then i just made sure i filled in any empty spots such as the seat belt bolt holes. After all that i ordered a 4x6 sheet of carpet from late model resto and went to work.
coupes and hatches are the norm but i still have yet to see one for a vert otherwise i'd be all over that sucker.
Anyhow.. did you get a chance to take those pics?