How can I run a load test from a groovy step?

I need to run a load tast for several days without stop to test the stability of the system. I only have SoapUI not LoadUI and when I configure the load test the duration is limited to 999 seconds (If I try to put in 1000 it converts the number to a decimal) or 999 iterations per thread. That means that the longest my test would run is maybe 2 hours but I need it to run for 7 days uninterupted.

My first thought is to have a groovy script that executes the loadtest inside a loop that will restart the load test every time it completes until desired completion time is reached but I don't see any examples of launching a loadtest from inside a groovy step anywhere.

Has anyone every done something similar or have any clue how to execute the load test from a groovy step.

If that fails is there some way to configure the run time to be longer than 999 seconds without using the user interface? If so what is the maximum duration that you can use?