Surely though if they are sneaking onto land they will have seen your lamp long before you see them. I doubt you would get an aggressive lurcher ome up to you they are usually fairly good at socialising dogs ive just wondered how to deal with the situation as i remember watching andy crow on fb talking about how he was shot at by a poacher and he called the police and 30 mins or an hour later a normal police officer turned up no armed response or anything so you are on your own basically. Probably best asking a gamekeeper as they encounter this more i suppose