Try sleeping with litter box on bed. If that doesn't work try 2 litter boxes, if that doesn't work, sleep on floor, put all 3 litter boxes on bed. Cat wins.
(hee, hee!) Best i can think of! Are they the boss or what?! Gotta love em! (I used to have a few bed peers but it was about too many cats- back when I had up to 30 fosters at a time! I remember changing the entire bed linens, then turning around to find so and so peeing right in front of me- i think his name was patrick- anyway- it is very aggravating but impossible to mad at them!)