I would not leave a horse out with a full clip. I can't imagine you need a full clip though. I'd start with a trace/irish clip and go from there and if more needed I'd go chaser clip so as to leave something on the topline with head and legs on. I'm a great fan of a blanket clip but wouldn't be keen on leaving no coverage on the neck of a horse living out. It depends a bit on where you are though. A sheltered field in the south being somewhat different from an exposed hillside in Scotland.
Mine already has a full clip. I leave legs and all his face on as I don't think it's fair to leave them with only half their face protected. He's a hot pony and still only needs light weight turn out rugs on. Last year I used his 200 gm rug a handful of times.