I was there for a few weeks a couple of years ago, sleeping in my van in that car park. The police did come round once, but fortunately while I had gone to Riglos for a couple of days. The police said they'd be back but never did, I think they just wanted to scare a few people away. Sleeping in the car park seems to be tolerated outside peak tourist season (July/August). But we were told that the hotel owner, who deosn't mind people sleeping in vans, will call the police if people are bivvying or camping in the car park. So not saying you definately won't get fined, but more not to worry too much.
On the other hand, it is ridiclous that they tolerate people staying in the car park, but then lock the toilets so people go and shit in the woods!