Another rotating header question (hard)

I have a site that I am converting to Atahualpa 3.7.1.0. It has over 270 pages. I want to have a rotating header only in the area's of the site where new customer are reviewing features of the software (which includes over 50 pages). But the rest of the site I want to have users see only a certain image.

Is this possible without having to put in CSS rules for each of the pages?

Also, most of these pages are within one parent. I created a WP Conditional Tag called 'is_tree()' so I can display certain widgets it a user was looking at that page within that tree (using the widget logic plugin) and added this to the 'functions.pnp' file.

While CSS might be out of the question because of the size of the site, is it possible to edit the code somewhere using this new Conditional Tag or something else.

Thanks.