Not sure if anyone else has run into this problem, I just found out the missing link after speaking with progressive industries surge protection tech.support.
I just bought (2) powerhorse 2000's to connect in parallel to replace the BEAST 7500 generator, did the job but,to heavy, to big and difficult to load and unload.
I connected the (2) powerhorse units in parallel connected the 120v/30a shore cable to the generators, NOTHING. no power, no lights.
I learned, the easy fix is to build a neutral to ground bonded plug.
youtube video -how to make a bonded plug for an rv
Not sure if this will help anyone but, I learned from this video.