For our car, I used a Hopkins kit. Easy enough for anyone who is comfortable with a screwdriver. For our Jeep (02 TJ), I added in a pair of trailer disconnects as the wires pass by the driver's seat, and plug in there when towing. I had all the ends in hand, so it was $0 in new purchases.
For the sides, I don't worry too much, as the MH rears are visible from the side (replaced stock lights with a less flush bright LED set), and I added some discreet 3m reflective tape to the front sides of each vehicle. Also added reflective tape to the rears, just in case the lights were to fail.
2016 SS 2250 E450