Are the outlets wired with the stab in connections on the back? If so, I would cut the wire off and connect it behind the head of the screw.
But first check to see if you have power on both of the brass colored screws on the side of the outlet.
Check for power by placing the meter leads between the brass screw and the green ground screw first. If you read power there, the move the black meter lead to the silver screw(s) on the outlet. If you don't have power there, then the problem is in the neutral side.
Does the outlet that has power have a Romex wire coming in and another going out to the next outlet?
Where is the closest dead outlet relative to the one that has power?
You might try check one of the dead outlets by putting the black lead of the meter on the skin of the trailer (a clean spot) and the red lead to the brass screw and see if you have power. The problem is on the neutral side if you have power.