I practiced down the street from our house before towing the trailer to the site. Nailed the backing between the tight gates on the first try! I'm so proud. : p
Picked up a bunch of ABS fittings and some really cool pipe protection for the penetrations through the galvanized pan. (thanks ReStore!)
Just need insulation, a bit more ABS pipe and some 3/4" sheathing and I'll have the trailer decked. Sourcing a large amount of the specialized screws that will penetrate the 1/4" steel is expensive but I hope it's as much of a labor saver as I think it will be.