With only six ewes you could probably hire a ram. That would be simpler to manage. However, as you already have a ram, buy a wether lamb at the end of the summer to run with him for company. A good stockproof fence should keep him away from the ewes as they come into season until the date you choose. Remember, the only sure way to programme lambing at a time to suit you is to plan the dates the ram goes in and comes out.