Correct. While storm surge can effectively push the shoreline far inland, the tremendous waves you see offshore just won't make it inland. In order to have 50-foot waves, you must have at least 50 feet of ocean below. For instance they built the Bahia Honda bridge (part of the overseas highway leading to Key West) 30 feet above sea level -- since the water is no deeper than 30 feet in that channel, it is presumed that waves could never crest over the bridge.

So yes, a 15-20+ foot storm surge will be devastating, and a few more feet of wind-produced waves can be expected to lash at anything just out of reach of the surge. There will NOT however be any colossal tsunami-like waves inland.