Do NOT do what I did..
*Stewpid trailer tricks*
I rarely travel at nite, but with my first little pop up, I found myself having to do so on interstates going from southern Oregon to Phoenix. I had my Element, which sat high, and the trailer was a motorcycle pop up that I could not see at all out my rear window because it sat so low. I had one of those Fresnel lens thingies in my rear window.. it worked fine during the day, but not at nite.
Anyway.. I stopped at a wally world and picked up on of those flashlights on a stick intended for boat sterns. I clamped it onto my rear bumper, switched it on and thought I was really stylin.. worked great.. until I saw the flashing lights
The nice hiway patrolman informed me that a white light
back there was illegal. When I explained why I had done it, he calmly looked at me and said "Ma'am, you are in the middle of the desert.. and this is not a boat"
I am sure he had a good laugh with his co-workers later that night. (I didn't get a ticket, thank goodness)
Now, for what I DO do.. I use my side markers and know how far the bumper is behind that.
Towing mirrors, or convex mirrors on your stock ones are very helpful. I use the stick on convex mirrors. My towing mirrors don't seem to do better than they do.