ORIGINAL: mez
Most everyone already answered you questions. I think you will be pushing it on size. According to the last post I must stand up wrong. The buckles of my safety harness hit the side rails unless I make a conscience effort to look down and see how to get them to clear. Even if the bottom doesn't come loose it makes noise when plastic hits aluminum.
When it gets cold and I wear winter or bulkier clothes I have to put my hands over the buckles from my harness, they don't fit with bulkier clothes. The bigger guys having no trouble with the size of the seat must have a bigger seat than I do.
Why don't you put fleece tape where your saftey harness buckles come in contact with the rails? That would eliminate the noise you speak of.