Flooring Tile - Slate tile on new and existing pier & beam floor.

Hello. I am redoing my kitchen. This remodel includes gutting the original as well as adding an extension of about 100 square feet. I want to lay slate stone tile over the entire area. The problem that the architect and I are facing is potential cracking from two sources. 1) the house is pier and beam with a clay soil that is prone to shifting, 2) there will be joints between the new and existing foundations.

Our goal is to engineer the entire floor system to minimize any cracking, and this is where I need advice.

The existing area has a tongue & groove pine subflooring (and I'm prepared to pull that out). The new will be new and can be what ever we want.

Can you give me advice on how the build up the subfloor and any special materials (like crack isolation fabric) that can be used to make a strong floor with the ability to absorb potential shifting, thus helping to prevent cracks?

Thanks in advance.

Here is what I'm thinking after more research. Any feedback will be appreciated.

On the 2x8 floor joists I will glue and screw 3/4" tongue & groove plywood.
On top of that, a glue and screw layer of 1/2" t&g plywood.
Using polymer based thinset (like MegaFlex) lay 1/4" cement board.
Apply a crack prevention membrane (RedGard)
Lay Slate tile using MegaFlex.

What do you think? Is this in the right order? Should the membrane also be applied under the cement board?

Thanks for you help.

If those 2x8s span more than 8' unsupported, forget it, not strong enough for stone, what's the unsupported span and the joist spacing?, then we'll talk.:)

The longest span is 8'. Most (75%) of the area has a 4' unsupported span.