The neutral conductor supplied by the local utility
q is intentionally. grounded at the source . If you examine a utility pole , you will see a ground wire running from the base of the pole to the neutral point of the utilities transformer . The neutral conductor is again bonded to ground (ground rod
,ufer ground or underground metalic water system
at the buildings service entrance along with all metallic parts of your service equipment (breaker panel ,piping ,meter socket. The grounding at the structure is a reduntant ground to the utilities ground . The grounded conductor ( neutral) and the grounding conductor (equipment ground) are not the same after you leave the service . The neutral is a current carrying conductor and the equipment ground is only intended to carry current in case of a fault .Your trailer frame is bonded to the equipment grounding conductor. not the grounded conductor (neutral) and only carries current. under fault conditions. You want the 120 VAC power to go out on the hot conductor (black) and return on the grounded (neutral /white ) conductor. The equipment ground
ground (green / bare is normally not a current carrying conductor. It is obvious from many of these posts that many do not understand the code or electrical
work and as Byron said need professional help.
I hold both a journeymans and masters electrician license
from the State of Minnesota plus hold a Vocational teachers license
and taught code to apprentices and journeyman for over 30 years so I am not just making an uneducated guess !