Well im glad you like the chassis so well. Ford makes some great ones. What was your Avg. MPG so far?
I agree with The Gritz. Take to the factory soon....You will get the bugs worked.
The Heater duct in the bathroom seems to be a common problem and a 5 or 10 minute fix. Mine did the same thing.
Take the cold air return cover off (4 screws)....the heater with the connecting ducts is right there. On mine the bathroom duct just fell out of the heater body. It has an alumium fitting that you twist on either 1/4 or 1/2 turn but I had to bend the little tabs to make it tight otherwise It would have fell out again. You can use some of that Alumium HVAC tape to hold all if them in place as well.
I do have to slam my door some (esp when its below 40 deg outside) but in order to have a tight seal and no rattles it needs to be tight. But yours sounds like it might have some other issues as well.
Good luck and let us know how it turns out.
2017 Axis / 25.4: Big Foot Levelers, Aims 1200 Watt inverter, Ceramic Window Tint, Full River AGM 6V batteries, Front Hellwig Sway bar / Rear Track Arm, Safe T Plus Steering Stabilizer, PD 4655 converter, Hard Wired Surge Guard, WEboost + WiFi Ranger, LED Headlights/Driving lights, TPMS, Surge tank, Tornado flush, Viair Compressor