I purchased this backup camera and plan on installing it on Saturday. There is a black, red, and green wire coming off the harness. Black is ground, red is power and green goes to reverse light. I need to run a wire all the way back to my reverse light from my mirror. However, I only have 14 gage wire laying around. Would it bad to run the 14 gage wire to the rear attached to the 18 gage wire harness? I think the wires are 18 b/c they are really small.