It worked fairly well and a previous owner had a plastic sheet in the drawbar box, which we used to cover the bed when packing in the rain at Blackall.
The bed still became a little wet, so I ordered a zipped mattress bag for future use. It's yet to arrive but my Drifta camping mat bags were delivered yesterday. Each will hold eight camping mats, including edges - which should further contain dust/dirt/mud. Fingers crossed!
The benefit of these mats is that a lot of dust falls into the holes. The pics in the collage are from our Roma packup, where much dried mud dropped onto the floor also. (I took the long-handled broom and pan with us and swept before each pack-up, to limit dirt being distributed through the camper when closing).
We took eight mats on this trip, which had been purchased at Emerald during our Wing-it Wanderings last year. My plan is to have eight mats for outside use and another eight for inside - with bags marked in some way. I'll buy a new set for inside use. Any older mats at home will be good for the garage area.