I rendered only the layer that contains reflective monoliths, which have the moving red cloth within their reflection.
In this shot, I have 2 layers of Monoliths: 1 in white and the other one in black.
Then I blend the two together by adjusting the opacity. Also, I add a flare effect to make them shine.
The bed footage got keyed out the red, and then it was used as an inverted luma track for another footage layer. That causes the rest of the footage to disappear, so now we have a floating red bed.
Tracking the marker on the CG footage is a way to go. The movements of the ‘Null Object’ will be identical with the reference layer. With some helping hands from Pin Constraint tool, the perspective will be controlled and adjusted accordingly to the reference layer as well.
Putting the bed layer on top of the CG background will completely hide the marker on the floor of the CG layer. Adding another null object containing the position data to make it feels floaty.
To make a shadow of the bed, duplicate the bed layer, crush all the color detail to black, decrease the opacity down a bit accordingly to the distance from the bed to the ground, tweak the perspective, and put the layer beneath the bed layer. putting fast blur effect over radial blur effect will do the tricks.