I don't currently have the spare time to do what you are asking.
Varying the infill will not accomplish what you want. The infill layers depend on upper and lower solid layers to hold the infill pattern in place. If you use a sparse upper and lower layer infill, the grates will not have sufficient strength to contain the carbon pile. The only effective way to affect airflow with a given air pressure is to vary the size and/or number of holes in the grates. The Filter to Motor adapter also has a grate component that would have to be modified.