Do not bond the neutral and ground. If the on board generator has the neutral and ground bonded then use a transfer relay that switches the neutral. I wire many of these type units. I got into battles with EMS vehicle builders who would put a panel board on the vehicle and connect the neutral and grounds together. When the EMS operator would remove the shoreline cord, they would get a shock due to the grounded conductor being lifted before the hot. This would briefly cause the chassis to become hot. If the shore power was connected to an receptacle that the neutral and hot were reversed (or a 3 to 2wire adapter was used and there was a poor or no ground, the outside of the chassis will be hot. As long as the neutral is kept isolated at least the chassis will not become energized. This is also why many older camper trailers trip a gfci (and why there are a lot of campgrounds with rigged wiring) Campers also have a small panel board and most used the neutral bar for both the grounds and neutrals. GFCI's do not like that!! Robert
