This process may lend itself to PPC a bit more than SEO. When split testing you will need to be aware of duplicate content, and considering that your ultimate goal is to figure out which landing pages are more effective, you will end up removing some of the pages anyway. On a large scale this isn't going to be as effective.

I would consider running a PPC account to test these pages and not have them indexed. Then, once you have a landing page that performs well, create it on the site and promote it with SEO.