As with so many things Greek, I think a lot depends on who you are, where you are and how bold you are. A man in a campervan (I think he was German or Swedish) was parked for the entire summer this year within spitting distance of the coastguard station at Sitia ferry port. The coastguards tried to move him on but he told them that, as his was a motorhome and not an unpowered caravan, there was no law stopping him staying there as long as he wanted. I have no idea if that is actually the law and in fairness to him, he was not causing an obstruction and the piece of ground was next to a derelict building, but it seemed to work. The coastguards blinked first and, as of mid November when I last looked, he was still there -- with his dog, which had made friends with several of the feral dogs that hang around the port. Similarly, there was a UK-registered motorhome parked for at least two months without a break, on a patch of rough ground beside the main highway near Sfaka, west of Sitia.