Moving Mat Issue

Hello Cow Crew,

I am having a minor problem that is turning into a major issue. I am working on a moving shot that dollies in and pans over to the action. It is an exterior shot and is night. I have created a moving mat that I have been using to have some Motion made train smoke appear as if it is traveling behind the building. As well, I replaced the sky with a moon that I have had to track to the shot.

Everything has been going well except for the fact that a portion of the mat seems to bounce a little bit against a portion of the building, not much, but enough to ruin the effect. I have tried going over that section but it seems very hard to fix.

My question is...is there a better way to to do this effect? For instance, some kind of garbage mat where I could use color key to key out the sky or create a mat from. I'm sure if I try to key out the sky without some sort of boundary I'll pick up a lot of blacks from the building.

This is one of those instances where I have come too far to turn around. Meaning that I have already put many hours into this and feel that I am close, but don't know how to proceed.

Any suggestions would be greatly appreciated. I am on Motion 3.

Peace and thanks...Ian