Sitecore 8.2 - How to share an item page in a multisite context decoupling content from layout

Question

I have the following scenario: a Sitecore 8.2 multisite solution with many products items shared between those sites. I'd like to share item as a datasource across multiple locations in different sites, decoupling this from layout. Could someone suggest me the best approach to solve my problem? keep in mind that solution should be easy, as it needs to be used by editor from experience-editor. Tnx in advance