They do exist in the Surface Navy. The example in my post of the enlisted SEAL who had to be a surface officer before going back to the SEAL teams, he was an E-4 before getting commissioned an Ensign, he didn't consider himself a Mustang (and neither did the rest of the wardroom) and he eventually went on to command a SEAL team. We did have officers in the wardroom who were considered Mustangs, but they were CPOs prior to their commissioning and their career path did take them up to DH level (and in the DH capacity, took a billet that could be filled by an URL SWO), but were not command-eligible and usually they retired after their DH tour. We did have warrant officers, but the warrant officers didn't consider themselves as Mustangs.