You've got to be a little careful when trying to speed up drying. Natural evaporation allows natural elasticity and adhesive properties to remain somewhat balanced. If you heat the upper layers too quickly, you might end up causing cracks to appear as the lower levels continue to dry. With only 1/8 inch or so, you're probably not in bad shape, but in general, I like to let "nature take her course"...my attempts at speeding things up usually result in either 1) having to start all over, or 2) repairing the problems caused by speeding things up.
Robert