Working on ideas for replacing bath with a shower.

1. The waste pipe exits the bathroom a few inches above floor level.
2. Lowering the waste may not be a good option.
3. I fancy a "walk in" concept with a long tray - with a bit of floor
beyond. Maybe a 1200/ 1400 long tray in place of the 1700 long bath.
4. What are thoughts on tray on legs versus building a raised false floor
where the bath had been to accomodate a tray and a dry step-in area? Would
this be more solid?