What do you mean that you dont want to use a plug? You can create a harness similar to this wiring:
Installed my VLEDS LPR. This helps the backup camera immensely at night. Used the Curt wiring harnesses with the 5 pin reverse light connection and it works great. http://www.vleds.com/shop-products/lpr/lpr-reverse-72-w.html...
5thgenrams.com
OR splice the white and blue wires off of your existing trailer harness. I would recommend against this. The addition of the Curt harness allows you to remove it or swap the harness if you mess it up. Splicing the wire incorrectly would just mess up your existing lines. I just did the same install the other day and it took a couple of minutes. I could it back to stock in about 1 min.