The documentation for SSI 0.5.0 indicates:
An ultra low-end configuration that we're looking at for development purposes is a virtual cluster on a single machine using User-Mode Linux (UML):

UML would remove the special hardware requirements otherwise imposed by SSI clustering.

I agree that UML would make life much easier for development and test. Can you provide more
information on the status and/or plans for CI/SSI on UML?