Where to buy extra large sleeping bags and rope?

I lead a local scout group and we are going camping this weekend in a remote region of the Ozark Mountains. So remote in fact, if someone was to scream bloody murder (hypothetically of course), no one would hear them! I was wondering how I was going to watch over 6 young boys all by myself, and then it hit me! I will just buy an extra large sleeping bag so at night I don't have to worry about the boys wondering off. Also, it will keep us extra warm. If they don't make extra large sleeping bags though, I'm sure we could squeeze into a normal size one. Oh, and also, where can I buy rope? Im looking for very strong rope. The kind of rope you would use to tie someone up with if you had too (again, hypothetically speaking).