Ideas for addtional support for bathroom cabinet contents

Just thinking...getting a piece of foam would allow you to "jam" things in place, so they don't move around much too. You will want to put all the containers as close as possible, and then cut a piece of foam to hold them in place, keeping a slight pressure on them.
You could adjust the foam by cutting it, as needed, and a fairly small piece from a craft store, would last a looooooooong time!