Just a comparison photo. The tear is 5X10, the gypsy caravan body is 11 feet long, not much bigger than the TD, and my guess will weigh about the same, the TD is a little heavy and almost all oak.
Fan-Tastic Fan framed in. I never like cutting holes in the roof, kinda like cutting holes in a boat bottom, So at first I thought I could put the fan in the wall, but it just wasn't working out. So, here it is framed in over where the galley sink will be. There is a slight curve to the framing, about a quarter inch top to bottom. I'll double up on the butyl tape when sealing the fan in place.
Some insulation and a little more work on the walls. See the framed square where I thought I could put in the exhaust fan? That was a weird idea. See the hole in the lower middle part of the side wall, It is a fresh air inlet for the air conditioner, the hot air will be sucked through the A/C and blown out the bottom of the ledge with a 70cfm squirrel cage blower.