Whether you can drive on 3 depends on the trailer and the load. You have to remove it and let the jack down to see if the hub is well above the ground. You're doubling the load on the remaining tire. If you're loaded heavy, you can blow that one purely from overload. Airstream might say it's ok but an Airstream is a very light trailer compared to one hauling cargo.
To say that a blown tire can damage the trailer is an understatement. That flapping steel belted piece of tread can rip a trailer to pieces. I've seen fenders torn completely off by one.
