This is a question from a non-builder. We are about to add the Almost 14 Seatback mod which will allow the seat to recline more, but I also want to add more legroom. Is there any reason structurally or otherwise we cannot add a fourth row of piano hinge to the seat pan on both sides to add another 1.5 inches or so of legroom? I don't know what is under the seat pan that might interfere with that new row of rivets. I would appreciate any thoughts and guidance.