Instead of more cloth which will make it heavier, how about inserting a balloon over the mold. Years ago, the makers of "Hobbypoxy" came up with a method called "Easy Does It" or something like that. Basically, after you put the cloth and resin on the mold, you push an inflated balloon over it...letting some air out as you do it. Done properly you have the balloon push out all the air bubbles as well as apply even pressure to the entire structure.

George

Edit: Guess I should add that you continue to let air out of the balloon until you just have the deflated balloon over the structure. The balloon is left on the structure until the epoxt cures.