I really don't know. Maybe you could put the cozy somewhere they don't go so much? I think some like to use their hidey houses for that, but others don't. If you have a loft, you could try using it there. I hope you figure this one out, sorry I can't be more helpful! =)
My pigs potty everywhere they sleep. There seems to be no stopping it. So I just put in 3 litter boxes hoping they will only use one for the bathroom and the others for sleeping. They still use all of them for both reasons.
My Sow uses her hidey house as a potty too! I think that's really the only place she pees, because when I clean her cage that's the only part thats wet! There's nothing I can really do about it, I've learned to expect it.
you could try training them like some other people on this forum have for floor time. Every time they poop, don't vacuum it up, just move it to the place you want them to go, and they'll be irked to do their business their in the future. Maybe they'll still sleep in the spot, but at least their poops wont be all over the place
One of my boars actually tends to do all his business in the same location (usually a corner) and everytime I clean the cage he chooses a different spot. Now only if I could get his brother/cage mate to do the same thing!