Looks like I skipped a couple of pictures. On top of the framework of skids, which are set 6' apart, are the 2x6 floor joists, which are set 16" on center (so the plywood sheets will split right on a joist.) The outside framing 2x6s are 11' 9". The outside joists are 8', and all the inner ones are 7' 9". That lets them overlap in different directions. On top of the flooring structure are the 3/4" plywood sheets. I put the middle one down first, to make sure I had everything split on top of the joists, but it came out okay.
All wood to this point is GC PT.
Everything is nailed with galvanized 3 1/4" nails, using an air nailer. I would love to use screws, but the time and sweat savings with a nailer are unbelievable, and I used a lot of nails. The joists are all toe nailed into the skids and 4x4s. If the building starts showing some separation, I'll go back and put some long screws in.
Here is the floor, covered with Black Jack 57. The can says a gallon covers 50 square feet. This floor is 96 square feet (8x12), and I barely made it stretch. It took a lot of work, but I think it was enough, even though it was pretty thin in some places.
I have to say the BJ 57 is as tough as they say it is. Really good stuff, like a painted on rubber sheet, but a word of warning: You'd better have a drill-based paint stirrer, because it is a little like stirring cement. It's that thick, and it separates and dries very fast. Get a cheap, wide brush and throw it out after. By the time you finish painting a gallon of this stuff on, you won't be able to get the brush clean.
You can also see that I've replaced the decorative blocks with bricks. I'm still going to have to stabilize them from horizontal movement.