Different styles with custom headers

[TJF]

We have about 600 forums. We have custom headers for each of them. What would be the easiest way to allow people to choose their own style while retaining the custom headers? The custom headers include different images/logos and links at the top of each page, so we need to retain the full header and not just replace the logo. Using conditionals would not be practical given the number of forums. Thanks for any help.