Ah! Rather than go down Mt. Libertry and the AT, continue along the Franconina ridge to Mt. Flume, go DOWN Mt. Flume (Good luck and God bless!) and rejoin with the AT. The area is very well signed, so you should have no problem joining up again with the AT. I forget if the ATC maps show this alternate or not. Or, as you said, you get to spend an extra day or two in the Whites. Not the worse thing in the world.