I just bought a 2021 Bighorn that I'll pick up this week. I traded in my 2015 Bighorn. On that one, I tapped into the constant power running under the rear bumper. I ran wire up to one of the holes in the side of the bed, inserted a low-profile rocker switch and affixed cheap red LED light strips on both sides of the bed. It worked great for the six years that I've owned it. I liked the red lights because they didn't kill my night vision, and I could still easily see everything in my bed. It didn't call out attention to strangers about what may be in my truck bed either.
I'll probably go this route again since it doesn't require a technician, a programming update, or running wire through the firewall and cab.