I also have a PP but was always worried about the cassette separating in the tray (Dual Cab) with ARB canopy and stuff flying everywhere so ive never used it.....
Ive got a Jimmys Thunderbox,I take a fence post hole digger and use Biodegradable plastic bags on the inside of the four corners, When finished,lift the lid and twist the plastic and tie off, then put down in the hole...Usually put a big stone over it or log...