Yes I am looking Mira Flight on screwfix, it will be joist then 18mm marine plywood then tray. No leg riser kit. Apparently they are the best made and silicone is good enough for theseI have been very satisfied with the Mira Flight series trays......stone resin with a quality capping and they come with a quality outlet.
They must be installed completely flat and on a medium that gives a cushion - the rep said that a thick bead of silicone was fine. Check if the outlet position suits you!
I don’t like the leg riser kits, and prefer a timber plinth if I need it raised.
As for an enclosure, buy the best you can afford - mine all came from Screwfix, delivery direct from the manufacturer.
John
waste is an issue as there are two joists on the way. see pic below, what do you recommend?