GY:
You should be able to secure the 92mm siamese fans to the solid wire supports which ThermalRight added to the earlier XP-120 design. The SI is exactly 25mm higher than the XP, but I believe all the sheet-metal dimensions and shapes are the same.
You just need to convince me that it adds something over a single 120mm fan, although I can see where it adds 25 square centimeters to the coverage. How you build it might be able to meet or exceed the air movement of a 120mm fan -- I don't know . . . . . I'd be interested how it turns out.