Take the following as face value only out of fear of future chastisement and because I am not a professional.
There comes a point when expectation and expense exceed practicality. The recommendation you stated above will no doubt yield great results, but even with that spec and every other foreseeable precaution taken, you may still end up with a crack or two. You seem understanding of this as you should be. If cracks are understandable and come with the territory, then really what is the concern with your soil?
Take a look at your driveway. It was no doubt poured on top of the same soil that you have in the back yard with no road base, no rebar, and minimal compaction. How does it look? The garage floor is more than likely 4" thick with either #3 rebar 24" O.C. or 8" WWM on top of a vapor barrier and 4" of sand/base. How does that look? The slab that your house sits on is similar to the garage floor. Is there heaving, separations or other issues? All of this of course assumes that you have a slab on grade foundation and a concrete driveway.
My point to all of this is that the deck around the pool will see less abuse than your driveway and your home's foundation - both of these were built on expansive soil. If it was that much of a concern then why not use 12" of base, a 12" thick deck with 3/4"-1" aggregate, 1/2" rebar at 6" O.C., and a true expansion joint in 8'squares? The expense is no longer practical for what your needs are.
My fear is that someone got in you head about your soil and has convinced you that you need to take action. I am not saying you don't but you have to draw the line somewhere. The biggest issue with expansive soil is moisture saturation. With good drainage, a solid base and the minimal rainfall that we receive, I don't really see any major issues that anyone anywhere else wouldn't also experience. The above mentioned prescription for your concrete deck is approaching the cost of correctly installed pavers, which I feel is what you really want and what was in the original design. Why not make a reasonable attempt at stabilizing your soil, provide good drainage, and ultimately end up with what you really wanted in the first place?
I stand by my beliefs that if your soil is extremely expansive, then pavers are the best option. What is everyone's fear with pavers?
- - - Updated - - -
If you do go with concrete, I previously recommended irregular and curved control joints. Reason being if you do get a crack (which hardly, if ever crack in a straight line), it can be cut with a
crack chaser blade that matches the contour of your control joints an essentially blend in with the rest of the joints.