I am in a similar position as the OP, except it usually stretches out to 10pm before DD finally crashes.
It is slightly better to get her to sleep on days when she doesn't have a day sleep, but she is a cranky pants so i don't know if i want to take that away on days when she does go down to sleep. (some days she just won't go down).
i don't have any magic tricks yet, but i am reading the 'no cry sleep solution for toddlers and preschoolers'. will let you know if i come up with anything clever!