I have been using wireless LED towlights for some time. They are magnetic and the transmitter plugs into your rig trailer outlet. They run on 8 AA batteries and the batteries last for around 48 hours (that's 6-8 hour days of towing. Here's a link to the website:
Wireless Tow Light Products
I just recently had my car wired so I will be selling my lights. I will probably put them on the classifieds for the forum.
Dave