Creating Word dos with several page sizes using Masterpages

[daicehawk]

I need to create Word outputs in Letter and A4 page sizes using MasterPages.
So far we do it by creating separate targets for each page size, separate identical (except for different page sizes) MasterPages for each page size) and separate TOCs in which the topics get assigned to the corresponding MasterPage.
Developing a project in this case means creating an initial "Master" TOC and then creating identical "slave" TOCs as many as there are page sizes just with the different MasterPage linking.
So every time a change is made in the TOC structure, it has to be made in all TOCs.
Is there a way to set page size as a variable or property of the MasterPage, or to use different MasterPages with just one TOC?

[daicehawk]

Seems like the most logical way is using conditions for different formats and inserting several (one per each page size) body proxies into masterpage. Havenot tried it yet, but I think it must work.