The steps mentioned below are what I took to wire my 40×48″ trailer kit. Please note that these are the steps that I took but you should consult and follow the instructions that came with your trailer.
1) Since we increased the overall length of the trailer tongue, we will need additional cable. Run the wire from where the harness came out of the tongue to the four lights. Cut these to length.
2) Solder or crimp connect the wires to the light.
3) After connecting the wiring to the four lights, I soldered the wires to the harness. For now, I let the wires hang until installing the deck cross members.
4) Cut the wood cross members so they are the same size of the metal cross members. I used pressure treated 5/4 x 6 inch x 8 ft deck boards obtained from a home improvement store. These will be used to mount the wood decking to the frame. You will need a QTY(6) – 5/4 x 6 inch x 8 ft deck boards for the deck and cross members.
6) I then cut and assembled the bed extension frame and bolted to the front of the trailer frame. The bed frame consists of two boards that are the same size as step 3 and four boards that are 12″ in length and the same width of the cross members.
7) I then installed the wood decking. You may need to use a chisel to notch an area for the hex heads that hold the trailer together. This will insure the decking lays flat on the frame.
8) After fastening the decking down with deck screws, I cut the bed to length. I left a 1 inch overhang between the wood cross members and the deck edge which resulted in a 64″ total length.
Go back to step 2 or go to step 4 of the DIY camper plan instructions.