Modular characters - how to attach head to the body ?

I am in a pickle here… I need to separate my character into body and head, because as one piece it has a way too many bones for mobile to handle (75 bones per mesh is max for mobile).

I am thinking that I should keep neck and head bones in the body (and animate body and head together), but export body and head separately (body will have neck and head bone, animated; head will have neck and head bone, not animated). In UE4, I’d need to attach head to the body so that neck/head bones in the head match same bones in the body, and then I’d need to to copy transforms from body’s neck/head bone to the respective bones in the head (so that I don’t get any tears in the mesh, between head and body meshes).

How can I do that and is there a better way ?

Thanks

P.S. Head has facial rig, so that’s why there are too many bones for a single mesh (for mobile anyway)