Tracking Multiple Sites Using a Single Cart and Checkout

I have a rather complicated setup that I want to make sure will work out the way I want before I head into testing and setup. Any advice or guidance would be great.

I have multiple sites, but they are all on the same root domain. These sites are all, for the most part, single pages but they must be tracked as entirely different sites. For example: - root domain - site one - site two - site three

The way I’m planning on doing this is setting these up as sites within Piwik and giving them each unique IDs and using setCookiePath on each site so I’m not getting any crossed wires if someone visits two or more sites. (accurate source and other metrics are crucial)

Now here’s where it gets a little more complicated (but I hope not too complicated)

All the sites I listed above are E-Commerce sites that all share the same cart and checkout system, for the purposes of this example

Now, I’m already passing multpliple variables from the product pages to the cart and my hope is that I can simply pass the siteID along to the cart and checkout in order to track. This way the ecommerce pages will be counted only for that siteID that was passed.

My major concern is that since I’m using setCookiePath, will that somehow screw up using that sideID on the cart and checkout at all?

Does this sound correct/possible?