Brad,
Save yourself a ton of time, money and frustration. Go buy this:
https://www.amazon.com/Hopkins-56200-Simple-Vehicle-Wiring/dp/B009SIO9ZW/ref=sr_1_1?ie=UTF8&qid=1489552222&sr=8-1&keywords=Hopkins+56200
It's a plug and play harness for your '15 JK. We and many, many others on here have installed that kit and it works flawlessly. It utilizes your stock tail lights, brake and turn lights. When those are used, the bulbs for them are mounted directly in front of the reflectors that are built into the tail light housing. That's the best and most safest way to do what you want to do. It's a piece of cake to install. Any questions about, PM me and I'd be glad to help.
We've been running that kit in our '15 JKUR for about 8 months now and it's great.
Scott
