Hi Ben,
I would use a Polygon object in a Cage-deformer set-up. (+ Cluster*)
Example file:
https://www.amazon.com/clouddrive/share/QRZuNL1LFLeZ7OXPmqjX4vjrCwC33KS6EXBNap2sCru
*The Cluster is typically used directly on the points of an object. The question about the FFD indicates the idea to limit the number of control points, which then influence a more significant amount of points. It feels like an extra element in the chain. Since the points that should be controlled of the final object needs to be defined as well. With such a selection done, they are re-selected quickly. Since I have no scene file from you, I might not see the need for that extra element. You certainly have your reasons, but I wanted to have mentioned it.
My best wishes for your project. Stay safe, stay healthy.