Just my experience, but don't add the deck pad exactly like they showed. You do want the pad feet, but I always tighten it just under the deck, and drive the post down with a t post driver. Make sure the deck pipe is in the corner bracket and that will help keep the pipe vertical. If the pipe footer hits the ground, then raise it again, and drive it down some more. I try to hit clay, and that may be a foot or 2 foot down, and that's plenty. I've got one 2 tier Tommy Dock deck that's held on a near 45 degree angle for years. You may need to use a block or screw a 2X4 to the dock to keep it level while you set the posts.
