I would advise against the bed rails...we pushed our 1st son's bed against one side of the wall and put the rail on the open side. Within two weeks he had broken it and it was useless. The company sent us another one, which we saved for our younger son. He broke it within a month.
What has worked better for us is to line the open side with pillows, or a rolled up comforter, then tuck in a top sheet over them so that it is secure. This has been successful so far in our youngest one who is sleeping in a high bed.
Also, I have seen online, the bed rail that looks like a big roll of filled fabric that you can attach to the top and bottom of the bed if you are interested in just buying something