Interesting, lets see if I have this right:
To apply a covering on top of another covering and get no bubbles, do the following:

1) Use trim solvent to activate the glue on the back of the monocote (works also with Ultracote?)
2) spray windex on the plane where you want to apply the second cote.
3) apply the second cote where the windex is, then squeegee out the windex, and it should now stick.
4) you can go over lightly with a hot iron

Sound right ?

Thanks for your help and patience
Mike