We have rented the past 3 years for only a month. And plan to do the same this year. We just wait till Jan and there are usually cancellations for Feb and March. We have rented Feb,March and April.
Last year for various reasons we could only do 2 weeks. We were able to find a villa in Chatham for the last 2 weeks in April. Someone had rented it for the winter but only wanted it for the first 2 weeks of April.
If you can be flexable. Already I can see there are cancellations for this coming winter. Check out
www.thevillage4rent.com. We have had luck on that site.
Good luck