Monokote on Monokote
Two other methods I've used....
Use Ultracote over monokote for trim graphics. The ultracote doesn't out gas as much as monokote, so you don't get the bubbles.
Run your woodpecker (or just poke some holes with a tee pin) over the area that the trim will go. When you iron down the trim, the gases have a place to escape.
Iron temp is really critical no matter how you do it.