Hmm, getting creative here, but if you don't wish to have something custom, and this isn't just to see how you do before you get a scrip for Pantoprazole or something (I saw your earlier post about GERD, but this photo helps me give you an answer), I'd take off the top mattress and take a pair of pinking shears down the center of your bed skirt from the top to about six inches from the foot. Then I'd just use duct tape to secure it in place again, with the skirt parallel to the floor. No one will see it between the mattresses.

If this creates a visible "hemline" at the top of the skirt under your head, an oversized comforter/duvet might help, the way you are making the bed now with it all the way to the top. A throw at the foot might also distract from the fact that your bedding is at somewhat of an angle. Good luck!