Combine pose with animation

Hi, so I'm not entirely sure if this is something Unity can do, since it's not really made for animations (just importing animations) but it seems like it should be possible.

I've got a character model where I've rotated the bones and such to make them look like they're slumping (I want to use it as a default pose for this scene) and saved it as a prefab. However, that's rather static, so I wanted to make them sway a bit. Since I don't want to affect the rest of the of the upper body, I created a mask that only affects the legs.

However, when I create a second layer on the animator and apply the idle animations with the mask, I run into this problem:

http://answers.unity3d.com/questions/607209/animator-component-makes-character-fall-through-pl.html

I've had the problem before, and solved it the same way, but the problem is I don't want to have an animation play on the base layer, since that would override the pose I've created. Currently the base layer just has no states.

I think I could solve it if there was a way to save the pose I've made and maybe turn it into an animation (just two frames with the same pose) but I don't think Unity has any feature like that. Hopefully I'm wrong. Any help would be appreciated.

Pics for reference:

Pose I created:

Layer2 is masked and the Base Layer is empty in the animator.

When I play the scene:

If I remove the animator controller, it works fine obviously. But then I'm stuck with that pose the whole scene.