I have no trouble with this:
let them sit out in the open overnight, with a slow fan on them. In the
morning, put them on top of a kiln as you fire it with a load inside.
THey will be TOTALLY dry by morning, and you can safely put them in the
kiln and fire SLOWLY...SLOWEST SPEED.
I've been doing this for years with no trouble. You're right, they must
be bone dry to be fired, but if you are ALMOST TOTALLY bone dry, you can
hold the temperature at 150 for a couple of hours to finish up the job and
then fire slowly to temperature. Do not set freshly finished work on top
of the kiln if it is at all thick, as it will crack and dry too unevenly.
Wait at least a day to do this. I was taught to do this at Arrowmont
School of Crafts in the summer (what a great experience) where they were
trying to move a two week class through the kilns as quickly as possible.
ALl the way through school I was taught to dry under plastic for a few
days, then put holes in the pastic, then lift the bottom, then finally
about two lifetimes later, remove the plastic. HA I never do that