Programatically export map clusters in QGIS

Question

I'm trying to export each microcluster of a large map into a composed map that shows the ff on an A4 sheet:

1) Cluster/grid box of the map

2) Larger index map with the pertinent region highlighted

Workflow for each cluster:

1. Shade the intended region in canvas
2. Reflect the shading in the index map (map composer)
3. Adjust the view of the cluster map (map composer, same page) (layers are locked for both map items i.e. index map and cluster map)
4. Save the entire file as PDF

Repeat 50 times. :(

Now, there's a LOT of clusters. I've spent a whole day on a region alone, and there are 5 other regions.

Is there any programatic way to do this?