[Closed] PlumbingTrackWorld - Riser Tray and Waste Pipes

The latest DIY project keeping me away from my bike:

I need to replace my en-suite. The waste from the basin and shower have to run above floors according to my architect father. (I cannot run them through the floor because I'll have to smash out several walls in order get the wastes into the soil pipe).

I'm looking at a Mira riser tray. I can see how I can run pipes under it, but I cannot see how I would run the waste pipes out of the corners of the shower tray. Th legs appear to be in the way. Surely the whole point of a riser tray is to allow one to run pipes under the shower and out.

Anyone else had this problem?