Selecting Style by Menu Item - what's the best way for Gamebox?

I am gonna use the Gamebox template to build a J1.5 site, but each section of the site has a different theme, which will mean different background image, different gk-wrapper etc, much as the current styles do via the template selector, but there will be 6 styles in all.

I know that I could duplicate templates and assign them by menu items using the Template Manager. I have also read the Joomla dev files which tell you how to assign different backgrounds, but could anyone advise me what is the easiest way just using the one template and selecting styles 1-6 rather than than repeating the whole template?

Thx in advance.