Here's the bus as she currently sits:
Overall view of the deck. The trex is holding up well as promised.
Galvanized fittings are rust-free, and no issues where metal meets wood
The cedar cross supports have a nice weathered look and are structurally fine:
For context, the bus (post-conversion) has spent its life in the southwestern US. For two winters it was in the mountains of New Mexico where snow is not unheard of, but the sun is pretty reliable about making a daily appearance.
It's a good deck and will probably look like the above photos for many years to come. Something that may work as a lighter decking material would be the composite decking that is hollow core.