Throttle requests (maybe at the IP level) for the prototypes, but resell hosting. Redirect your third-level domains transparently for the hosted sites - make i

Throttle requests (maybe at the IP level) for the prototypes, but resell hosting. Redirect your third-level domains transparently for the hosted sites - make it dead easy, just a matter of clicking a box to "add public hosting". Then keep the prototype there as the testbed for new development, with a button to "Click to publish". That will take you, what, a whole day to set up? It's a no-brainer.