Remove 50amp genset and replace with 50 shore power

^^^ This ^^^, what Dutch said. It will be simple, inexpensive, and you will have the best of both worlds; you'll have both A/C's when on shore power, and still have the generator, which powers everything already. The only new procedure will be you will have 2 cords to plug in to the pedestal; the existing 30A shorepowr cord, and the newly added 20A service which you'll simply plug in to oneof the 20A/120V receptacles in the power pedestal.