Change duration of a MOGRT without effecting the background playback speed

I am creating a MOGRT for my team to use. It is a simple title that animates on and off. I have already set protected regions for the intro and outro. The problem I am facing now is that there are moving elements in the background of the title sequece that I need to playback at the speed throughout the animation, regardless of the duration set by the user. If the user would shorten the MOGRT in Premiere, it is okay for the background to be cut short, but it looks awful if the background elements are moving one speed in the protected regions, then changing to adjust to the time diffenerce.

Is there a way to lock a layers duration in a MOGRT to prevent its timing from changing? Again, it would be totally fine if that layer is cut short. It is just some movement in the background. 

Thanks!