upfront starter themes

I am currently building a wordpress site for my boss and i will be using the themes from upfront however my boss wants to see all the themes with some of our content on it and i have only the one domain url to work with how can i show all the themes together so he can choose which one he wants normally i would just change theme to see how each one looked with some of our content but he wants to compare side by side please help :slight_frown: