If you hug the right side of the road till and watch your right mirror, you will see when you drive by your spot. Now the camper is in front of the spot. Turn the wheel slightly to the left so you are now driving toward the edge of the road on the left (drivers side). This will cause the tow vehicle and trailer to begin to turn (left). Angle it so you can see the camp site pad in the right mirror beyond the end of your camper as you pull forward. Once the rear of the camper passes the camp site, you can pull slightly a bit more forward. You are at an angle to the camp site now, a V type angle. Now begin your turn backwards and the trailer will go right in. Once you start your turn, the rear of the trailer will be out of view of the mirror. If you have motorized mirrors, learn to turn the mirror as you are turning the trailer and tow vehicle and backing in on the "blind slide". By moving your mirrors outward, you can keep them focused on the end of the trailer. All you need to do is get the rear of the trailer started in the spot. Once started, then you can readjust your mirrors to follow the back of the tow vehicle and simple back the tow vehicle into the spot, the trailer will guide itself. All you need to do is have your spotter watching the back of the camper to make sure you are not over-turning and potentially backing into something, like a tree or a picnic table. After a few attempts at this, you'll be able to back in without assistance (but a spotter is always a good thing).
Remember, hug the right, pass the spot, then move to the left at an angle so the trailer and tow vehicle are still straight, but at an angle to the campsite pad. Then begin your backing in.