S.W.
Hello M.,
You can get an out of district exception to send your son to Larchmont, a friend of mine did that, she met with the principal explained they were moving into the district (as soon as they sold their other house) and got the paperwork done with NO problem! That may solve your problem.
There are also other options, you can always homeschool your son. There are LOTS of resources and homeschoolers in the area. You can find out more info a www.vahomeschoolers.org.
Good luck to you, S.