Corner Pin a layer with mask (corner pin should fit the masked object)

Hi,

I am trying to use aftereffects with ae syphon to do some projection mapping. I thought it would be really easy but of course it is not...

I have a rectangular image, I need that to break in the middle (corner pin but also in the middle) I tried several things like bezier warp, simple corner pinning etc. but I couldn't find a simple solution.

So my solution was to mask a part of the image, use corner pin to pin it to the spot, duplicate layer and invert the mask and corner pin that one as well.

When I apply a corner pin on the masked layer, it grabs the original image, how can I make it grab the border of the masked image?