I believe that the test keys will not allow you to create a new company in GP. The Fabrikam company is 'special' in the sense that it has everything enabled/set up in it for testing and training purposes. In some ways this is good, as you can test something quickly. However, for what you're describing, testing setting up a new environment and preparing it for production rollout, you will most likely be significantly hampered by only having access to the Fabrikam company.
I agree with Richard, work with a GP partner, purchase the GP 2013 Starter Pack license (this is the minimum possible for GP 2013 and already includes 3 Full users) and use that for development.
