Wow, absolutely beautiful deck! Stunning! And I'm sure all the research and planning that went behind this would make my head spin. Congratulations on your completion of such a huge and fantastically successful effort!
A good way is to take a piece of cardboard (about 40-50 cm = 1,5 feet). Hold it between your nose and the border of the images. Normaly your eyes should automaticly try to combine the two fotos to one now.