It depends on the bed if this is possible or not. Because 1 tile is either above or below the player, and in this case the player can walk behind that bed, so the top tile of the bed is always in front. I think there are other beds where this is possible.
I tried all beds that I could find, but I couldn’t find a single one that works to make a character look like she/he is lying in it. The only one that comes close is the sleeping mat in REFMAP indoor, but that one has no blankets, so it looks like the character may just be standing on it.
After I rework the engine to support water, this shouldn’t be a problem anymore, and so tiles can be both in front and behind the player, depending on where the player is.
That’s great! I’ve voted for the feature 🙂