The idea that children need 12 years of public schooling in order to receive proper socialization is greatly over exaggerated.
Most literature in clinical psychology will agree that if your child isn't socially acceptable to other children their own age by the age of 4, you as a parent have largely failed to socialize your child properly.
When my wife and I decided to homeschool our daughter, we did several months of research into each particular curriculum (mathematics, science, history, etc.), and decided which curriculum would be best for our daughter to study.
In my home state of Nebraska, home-schooled students can apply for a University of Nebraska diploma. Once they've passed a certain set of tests, they're given this diploma that serves as an equivalent to any other high school diploma in regards to enrollment in higher education.
If the eventual goal is higher education after homeschooling, there's really no reason, or incentive to try and "cheat" your own homeschooling curriculum.