Hi I'm new here and I want to tow my 2006 Caravan behind my motor home on a dolly. I wish to run the caravan's turn/stop and tail lights from the motor home lights. I want to run 5 wires through the undercarpet cable tray that travels down the center or the van. I also want to tie into the van wires using blocking diodes under the rear hatch plastic sill trim. My question is were does the front of the cable tray start and how can I access the front end of the cable tray. I think I know which wires are which at the back.

Thanks AL