> It might also be advisable not only to use thick decking, but also run two layers . . .

I plan to run two layers of decking - 5/4 each. I've got a lot of white ash that I've been thinking of sawing up for the top layer of the decking. (The primary species I have to work with are hemlock, maple, ash and cherry. The maple is reserved for sugar and some of the cherry is gonna go into new kitchen cabinets one day.)