Default [Q] Flash vzw devices to sprint to test network coverage

I am considering switching to sprint from vzw, and obviously my biggest concern is coverage. I have a couple of old phones, a droid X and razr, and would like to flash one of them to sprint radios, not to actually activate and use on the network, but just to test coverage at home and work. Is this at all possible? Any ideas of where else to find information on this? I have searched xda as well as google but am not finding anything. TIA