marmox showerlay install help

[klunk]

Hi,I'm installing a showerlay tray in a wet room I'm doing I was going to lay ply in-between joints to support tray put tray in and cover rest if floor with 18 mm ply with 6 mm tile backer board on top of that,But looking at the install instructions online they have 18mm ply on joint with tray on then 20mm marmox board on top if that by time I have the tiles on which are 10mm I'm going have a step which they don't want so can I do it first way I said?

 

[klunk]

Should say 18mm ply on joists then tray on then 20mm boards round , dam predictive text