Yes. Some 5th-wheels do have the antenna high up on the ceiling where no one can reach it without a ladder. That's why they installed the powered rotating Winegard.
There is no other choice that will work as well. Considering your choices are very limited (1) and no other will be found close by (considering fuel), you only option is letting the dealer install the replacement.
Otherwise; deal with reaching the crank and install a Winegard IV and Sensor Pro. Only a fool would purchase a Omni-directional antenna unless they were on a seasonal site within 25 miles of the closest transmitter.
