With most content management systems (CMS); you do not make changes to a single page’s layout. You make changes to a template, and that change is reflected across all pages using that same template. This makes it difficult to test large sites for SEO purposes as the CMS is an all or nothing change.
You can use paid search to test your template change ideas. Just as with homepages, you do not want your paid search team to design these on their own as your navigation and other offers will be stripped away to try and increase conversion rates. With your templates, you need to think about site navigation and page information for organic ranking purposes.Therefore, create a few static pages outside of your CMS; but work with the SEO team on how the pages can be laid out so that if the new template is better, it can be implemented across the site without hurting (and hopefully, helping) your current organic traffic.
If you offer hundreds of products, do not just test a single ad group with a new template and then roll our the changes. Make sure you are testing enough different products and services to be confident that the new template will work for all of your products.