You will likely get lots of suggestions recommending you look at other projecter with more suitable throw rates etc but assuming you are set on the 5700, I would think your only choice is to mount it below the height of the cross-beam and then angle it up slightly to whatever your desired screen height is. You will then have to keystone the picture to compensate. For some this is a no-no. For others it is not really noticeable. That is up to you.