Start the whole thing by doing an "S" turn.
This is assuming your site is on your left side of the road. If it is on the other side then just reverse the directions.
1. Work you way to the left side of the road before you get to the site.
2. When the front of your truck is near the corner of the site, turn right so you start across the road. Watch the tail swing of the trailer so you don't sideswipe anything near the edge of the road.
3. About 1/2 way across the road turn left so the front of the truck just misses the things on the other side of the road.
4. Stop when you reach the left side of the road. Your truck should be facing the left side at an angle and the trailer should angled back towards the site.
5. Start your back into the site and follow as necessary with the truck.
After a few tries doing this, you will know just how to and when to start the maneuver and how far and tight to make the turns.
The track you just made looks something like the letter S and will position your trailer just right so you can usually back right in without the front of your truck hitting anything on the right side of the road and will allow you to jacknife your trailer just about as tight as needed to get in. You may have to pull ahead once or twice to straighten up once you get in the site.
It sounds harder to type and read than it really is to do.
Good luck. :)
Barney