Rails migration hackery with ERB

How do you create a rails project if you don’t know the schema in advance?

Jerome had a really unusual set of business requirements for his first rails project: customers that will each have their own dedicated server, and have to be able to specify their client list schema through a web-based interface.

That’s a pretty ambitious task for a first rails project, don’t you think? Here’s my take on the problem. If you have a simpler solution, please propose a refactoring.