I have the moultrie tree mount, besides the screw tree step attachment that comes with it I really like it. The screw in thing is hard to start, and mine broke the second time I moved it. I ended up buying some EZY tree steps and welding bolts on the end to fit the tripod mount. (I assume the D40 has the tripod threads on the bottom of the camera like my I40, might want to check to be sure)

The actual mount is awesome. You just loosen it point it where you want and tighten it up. Couldn't be easier.