Per Autoblog: "It's not included on the initial WT models."
I don't believe they confirmed one way or the other on Trail Boss. With all the interest in it, I think it will eventually trickle down to other trims in an options package, but I definitely wouldn't count on it for WT models in the first few years.
“WT estimated MSRP starting at $39,900 + DFC* with optional features and content such as up to 20,000 lbs. towing*.
RST trim offers available features including Multi-Flex Midgate with passthrough, Panoramic Fixed-Glass Roof, 4 Wheel Steering, Wide Open Watts Mode and more.”