You should not be able to see any wires under the trailer other than the ones leading to your breaks. All the light wires are inside the trailer running around the perimeter of it.
Did you cut off the old lights on the outside and simple connect the new ones to the old wires? If so thats not going to work out well for you.
If you havent already done so, remove your passenger side (right) rear bench (easier to do than it sounds) and pull away the rat fur by the rear light (you may have to cut it to do so) you should be able to see the all connections you are looking for and where they go, including the Green one which is your side markers and tail lights
. Remove the old rear light wires and their connections and attach your new lights into the trailers main wiring system.
You may have lost your side running lights due to pulling on the tail light wires as in MHO Scamp
doesnt do a great job of making tight wiring connections and they may have just come lose. I was taught to use heat shrink wrap connections to protect them from working loose and from moisture.
Scamps wiring colors assuming no one has messed with it:
Green (TM) - Tail Lights
and Marker Lights
Red (LT)- Left Turn and Brake Light
Brown (RT) – Right turn and Brake Light
Black (S) – Interior 12 volt lights and Accessories
White (GD) – Ground
Yellow (A) – Brake Lights (Foreign Stop) or Backup Lights
Blue (Large connector only) – Electric Brakes
Hope that helps.