cswca ... I have all my Astak cams on ninjas and they work great. If you line up one of the mounting holes in the cam base with one hole in the ninja it is fairly close to center. You can drill a small pilot hole for the other 2 and use small self-taping screws. (the top of the ninja snaps off)
Whats nice is the way the cam tilts down on its own base, you can tilt it all the way forward which makes the ninja tipped back a bit to see level. Then when you tilt the ninja all the way forward you can almost look straight down. ( great when the cam setup is mounted high up).
One other note on the 2 you will mount in a fixed position. If the base is mounted upside down you will have to flip the camera on its base. The cam is held on by 2 tiny screws and if you look close you will see 2 tiny holes on top of the cam body. (If you don't do this the image will be inverted.)
Have fun.... those cams are great in low light and no light. They can flicker a bit in very high sunlight though so watch pointing into the sun.