The bed has a mattress made from a block of rigid foam.
it occurred to me that some weight should be shown so a shallow cavity was dug out.
The block was covered with some scrap material.
Then some pillows made up and a quilt.

The quilt has a thick woolen layer inside it with a shaped area
cut out to give an illusion of sinking in under her bodyweight.
The carpet was some paper backed foam I had laying about.