Rhino is still left in the dust by Wolfhound, and even Poodle
Okay, sure, 3 Wolfhounds is only a bit over half the Rhino's thrust at similar mass, but at the scale you actually want that much thrust, a few tons here and there doesn't matter. The Rhino right now is eclipsed in the tech node it's unlocked at by clustered Wolfhounds.
Even in the basegame, the case for the Rhino is questionable, as the Poodle comes pretty close, and extra vacuum Isp tends to win out at high masses.
Also, the Rhino's big bell, like the Wolfhound, would suggest a high vacuum Isp, but it's instead below that of the tiny Terrier.
I recommend the Rhino's vacuum Isp be increased to at least match that of the Poodle, if not that of the Wolfhound or more.