Why not consolidate all of the item tables into a single doctype, and hide & unhide fields based on parent document? It would help to keep a consistent look across documents.
@cpurbaugh, why keep a lot of fields with null values in the database?
And, has another detail, keep it seperated, makes sense under the principle of single responsability, that means, that 2 distinct informations can’t share the same place!
I understood were do you want to reach, but it’s not a nice pattern!