Looking at what you want to do, using something like Jenkins to kick of a specific test or set of tests might be useful. We have several projects that we run using Jenkins, both kicked off manually or kicked off according to a schedule. It's pretty easy to do and can be set up so that the tests are running in their own workspaces, and thus isolated from each other from running the test point of view.
Thus you don't need to create the test projects each time, the test projects are defined once in SoapUI, but you just choose the test project you want to run from an existing list of test projects. Might mean you need less groovy skills to programatically create SoapUI projects on the fly.
Just a thought and a different approach that might meet your needs.