Since it's only the ones on the bump out, it's probably an issue with the line between them and the main trailer. Like others have said, first pull the plugs. Most likely one of them has the power from the main, then passes power on to the other. You need to look here to see if there is power from the main. If there is, the source of the problem is in that box. If not, then you need to work backwards. Go from that box into the panel you saw the tech remove and locate the same wire. Check for power there. If you've got power going to that wire, but not into the box with the plug, then the break is in between the two. (possible due to whatever flexing was involved with putting the bump-out out.)
If power's not even going to that wire, then you need to start opening up walls, etc.. of the trailer to trace the problem back even further. Always working along the same line to the next junction box, switch, outlet, etc... until you find power. Once you find power, the issue is at that point.
There's no use crying over spilled milk, unless it's on your keyboard.