Interesting. I ran a couple of videos on YouTube and it doesn't appear to have any ducting for heat. Surprised as our little 19H is ducted throughout. Going to be tough to get heat up into the front bedroom without, but there are no spaces for above floor ducting and no in floor ducts evident anywhere.
There is fully ducted AC throughout, but unless they tied into that by running a duct up behind the fridge, it won't serve the furnace. I don't think I've ever seen this done.
You might consider adding supplemental heat to the AC unit if it is not already there. This would be ducted throughout the trailer but only works with AC power, and really only adds enough heat to supplement, not replace, the propane furnace.
2011 Jayco X19H (purchased 2015)
2008 Jayco 1007 PUP (purchased new, traded for the X19)
2018 Nissan Titan Midnight Ed.