I am in South Florida and have about a dozen vandas. All are hanging bare rooted from various trees in my backyard -- either in wooden slatted baskets, the little plastic/mesh baskets (like the one yours is in) or just hanging from wires.
I don't use any moss on mine, since my experience is (and I have been told) the roots thrive when they are free. They are outside all year round, get pretty much full sun and rain. Our weather here in Miami is probably just like yours. If you water early in the day, it should give enough time for any water in the crown to evaporate. Good luck!