Backing your trailer..
In 2007 I took Dick Reed's driving course in California. This is where I learned this technique.
Now what I am going to say many will disagree with me. However if you practice this you will find it is a lot easier than having the DW on a radio, in back yelling or getting angry with each other and no one gets run over.
As suggested in a previous post, I use some small orange cones or some line in the camp site where I want to position my trariler. You can also use a number of the orange leveling lego blocks. Doesn't hurt them when you run over them.
Position your trailer beyond the near edge of your camp site, and back up turning when the bumper or back of the trailer is at the nearest edge. Now the real weird way. I have my DW drive. (and yes many back with their hand at the bottom of the steering wheel which does work well.) My DW will drive with her hand in the normal driving position. I will look all around the site for things that will cause a problem before we begin to back. With my hand on the driver side mirror (keep hand on mirror at all times) I tell her to start backing. She does not have to look around or anything just turn as I instruct. As I am watching the trailer go backwards and I want it to turn right (that is my right) I tell her to turn right. As she turns right this will move the bottom of the steering wheel left... get it??. I tell her to bend it easy, more, hard or whatever I want and I guide her back giving instruction as I see them when she is backing. If I am not sure how everything is going I ask her to stop and I go look where the trailer is overall positioned in the site.
You should practice in a large parking lot with cones or whatever you can make a camp site area with. I will park the rig and place cones around the trailer, then pull out and work to back it into my cone camp site.
The only way you will get better is to practice, practice, practice.
As for the T/H my Ford mechanic told me to always be in Tow Haul when pulling anything. I also use T/H on hilly or curvy roads. Keeps me from having to use the brakes.
FWIW
BC