A little different approach to the tape on the windshield that rgatijnet1 posted. Park so the right side tires are almost touching the parking lot line. Put a small piece of tape on the inside that touches the line when seated. You can do this by yourself.
Only glance at this reference to check where the rig is when you are looking way out front. With practice you will stop using the tape as with time you will get the feel for where you are. I would leave it on so in construction zones you can use it to keep as close as possible to the right so you do not have to worry about the left side.
While in the vacant parking lot, put out a cone or coke can on the end of a parking strip on the right. Use it to see if you are going to miss it in a right turn. Turning too soon and not turning the steering wheel fast enough once you start the turn are two things that help you scrape the side of the MH. By hugging the center line before making a right turn will help too. On occasion there will not be anyway to make a right turn so go ahead to the next street and then make three left turns. If there is not any traffic you can go 20' further than normal and make the turn in two steps assuming you are not towing a car. Once you have to stop, turn the steering wheel all the way to the left and back up so you can then finish the turn on the second time going forward. I've even made tight turns that were more than 90 degrees by doing it in three parts.
Relax, look further out and use your mirrors.