Despite not having the right size ball to hitch our trailer up, not to mention that we don't have a truck (had to rely on family there), here we are, parked at the build site at last.
To give more head space inside, we're using a deck-between, with drop axles, and also going to use the trailer itself as the subfloor (rather than building the subfloor on top of the metal). Thanks TinyHouseBuild for that advice, I think we'll appreciate the extra room when it comes time to sleep in the loft! Attaching flashing directly to the underside of the trailer poses its own challenges, however...
It didn't occur to us until we were about to attach the aluminum flashing how difficult it would be to work around the trailer wiring, not to mention axle attachment points and other obstacles.
From below, you can see how we became good friends with tin snips in order to fit the flashing around obstacles like this tail light. Later, the aluminum tape and I will have some bonding time to fix how messy I am at cutting with tin snips.
One more shot from the perspective where I spent most of the day. From this angle, it looks like we've made more progress than we have. The aluminum flashing is only 24" wide, so it will take 4 long rows to cover the underside of the trailer. Build day one has ended with only 1.5 rows done (but we're getting better at it, so we'll see how tomorrow goes).