Wordpress knowledge base plugin that does't use blog posts

I need to integrate a knowledge base into a Wordpress site.

The knowledge base must offer
– multiple products / clients
– content restriction by post, topic and product/customer
– minimalistic design
– must not use the Wordpress blog-structures!

The site has a very distinctive and heavily designed blog/magazine. All plugins I could test rely on the blog-structures within wordpress, thus showing the design of the blog. This doesn’t work for this site, as the layout has to be completely different from the blog.

Does anyone know a plugin exists that I can use for that?
Thanks for your recommendations!