Hi!
I think that don´t understand you clearly:
1. Backup OSX via Time Machine.
Two week ago, I did install El Capitan (clear install without TM Recovery) and I take long time , I can´t allow me this again
2. Break the Fusion drive in Internet Recovery Console.
I remember you that I haven´t Fusion Drive, this step isn´t necesary.
3. Split the SSD in half ~ 60GB each.
4. Use one half to install Windows (recommendation is to use the lower SSD half for Windows). Please install W8.1 or higher using EFI.
I understandb you say break in 2 parts SSD (half space aprox.) 60Gb first position to OSX and second for Windows,
5. Create a Fusion drive using the upper 60GB and half the HDD as a Fusion drive and use Migration Assistant to restore OS X from TM.
6. Use the second HDD half as D: for Windows and install applications on D: as necessary.
2 steps don´t understand.
First, you want to I create Fusion drive with one half of SSD and half of HDD to install OSX? Fusion 60 SSD + 1,5Tb HDD more or less.
Second, Install Windows 8.x + in other half SSD and them use other half or HDD to App from Windows?
It makes no sense to me... use windows occasionally, lose much space with this steps.
Fusion drive It´s very slowly tham separate physical disk...