Hey There
Goodness I hope I am not too late to answer your question. Maybe you are taking the fall and winter to decide.
WE have a new 2017 Pioneer P276 5th wheel.
YES we installed (camping world did) our 2nd unit in our Master.
IT IS DUCTED.
Cost approx. with install $1100.00 Worth every penny.
We called Heartland directly, gave the guy our VIN and they provided us specific details to inform Camping World "YES" our unit was ducted.
We knew our plan was going to be to add this 2nd ac unit as soon as we purchased this great 5th wheel.
You will be very happy you did. SUPER cold Master on those hot hot Southern days and nights.