there is an island right above Carbondale that is owned by the town. Jeff Jackel parks and rec director of Bondale has always wanted to open up a campground on it. If you call the town and ask him about it He would give you the specifics for camping on it.
carbondale co - Google Maps
But at the flow we have right now you could float from Aspen to Glenwood in about 4 hrs.
Peter