Coupon dedicated to an item and customer

Hello,

we are going to start a Kickstarter campaign in the next month. The products are 3d printed miniatures.
But instead of using a crowdfunding service (i.e. crowd ox), backers, who already paid for the product on the KS plattform, get a coupon that is linked to there account in our webshop.
Is it possible to create a customer account in the backend with the backed item in their cart with 0 EUR?
Our would you recommend another way?
Thank you very much in advance!
All the best!