I think a lot of the problems are the exception, not the rule. These things do happen, but it is not something that will DEFINITELY happen, if that makes sense. It could, but hopefully not. That being said, I think on the curb on mainstreet is one of the best places (which requires sitting VERY early) because there are a lot of cast members around for crowd control and souveneir sales, which makes it more difficult for things to get crazy, and if you're in the front row, you can more easily get attention should you need it. I think the towel sounds like an EXCELLENT idea, and that people are a lot less likely to step on your property.
My grandparents have also enjoyed sitting at the train station. They said it was very relaxing, with a great view of the parade!