MarketPress - protect eBook downloads

I've got a client that wants to sell eBooks (PDF files basically) using MarketPress.

He's concerned about file sharing and piracy, so a Google Search turned up a PDF Stamper for WordPress:
http://www.tipsandtricks-hq.com/wp-pdf-stamper/

It dynamically stamps a PDF file with the customer’s details (e.g. name, email, address etc.) upon purchase.

The plugin says it works with (their own) WP eStore plugin, but there are also instructions for Third (3rd) Party Integration (HTTP POST and/or GET methods).

Any thoughts on how we could get this working with MarketPress?