Hey Steve
I've got an 06 Fronteer, Probably the same vehicle. Your almost forced into getting a Factory wiring harness.
And its pretty weird how it all hooks up too.
Most of the work and connections are on the passengers side????
I've been wiring vehicles for years and unfortunately these vehicles...and many others are considered "Smart Car/trucks".
Which in this situation means if there is a heavier amp draw on a line.....like an extra light from, oh lets say a trailer, the line will simply shut down, so it won't blow a fuse.
I liked it better when cars/trucks were dumb.
When I was looking for my harness the only reliable place was at the dealer. Anywhere else I looked knew as little as I did about them.
Happy Trails
Len