We did it! We got some strangers to sit through our prototype. It didn't happen in a lab, we kept it contextual to what the prototype was trying to address. So we met people as they completed their transactions, and asked them how their experience was, and if they'd be interested in exploring a different way of completing this task. Also, we have a gift for your troubles.
We'd conducted some telephonic surveys as well, but found the information they were willing to share, weeks after they completed their transaction, lacking.
We'll be continuing the prototype exploration with customers this week. Fun fun fun!