It's not the static weight of the bikes and hitch that is the danger but the weight created by the shaking up and down motion when under way. That 80 lbs can increase 3 fold and more creating the possiblity of the coach shell to separate from the frame. 'Perhaps' that may not be a problem with a 16' coach....I don't know. Airstream has just introduced a bike rack specifically made for Airstreams but again I'm not sure if it's for you.
Neil and Lynn Holman
Kirk Creek, Big Sur, Ca. coast.
1966 Trade Wind
1971 Buick Centurion convertible
1969 Oldsmobile Ninety Eight