We find Tibbie Shiels ideal for a quiet weekend just chilling, the site is nothing fancy it does have showers and facilities although we haven't used them. Only other thing there is a pub, a loch and stunning views. It's less than an hour from us and only about 17 miles from the M74, very narrow road in places but worth it.
http://tibbieshiels.com/
http://tibbieshiels.com/