if your desperate for somewhere to go, and you have the landowners permission then id just do it, if you can get a static on the land for a grand then thats probably cheaper than finding a property to rent with deposits, months upfront etc etc. its then up to the council to get you off, or rehoused. how long you stay will depend on the fight you put up. my only concern would be that the landowner could be in for some grief as well, however, a succesful right to stay could be to the landowners benefit.