Somewhere on this forum, but more ;likely over on Stuka Stunt, John Miller did a whole description on just this process, done this way on purpose. Put down a layer of silks pan and dope as a base for iron on coverings. The iron on has more of a base to adhere and cling too, doesn't wrinkle once it's shrunk and sealed down and lasts a long, long time. John is a member of both forums and would know more of the details. You might find it from a simple search.
Type at you later,
Dan McEntee