I am currently trying to install a simple train horn. However the wires must run all the way from the trunk to the battery. I know of the grommet next to the gas pedal and I will use that for install my switches. However I can't find a grommet in the rear of the car to get the wires from under the car into the interior and then run them up the side foot panels. is there even a grommet in the back ? If not what's a solution?