I purchased the 5 piece mat set from Monster Motorworks and am using the cargo mat for this purpose + extra acoustic dampening (the vehicle is very quiet already).
I keep some black moving pads purchased from Harbor Salvage. They are handy for spill control and also blocking items in place and provide thermal protection for coolers and to keep the sun off items in the cargo area when I bring equipment along for business. They also catch mud or slop from dirty cargo and can be machine washed (such as when our dog tossed her cookies on the way to the vet).
I also keep a couple of straps in a black bag in case they are needed to keep propane tanks and other odd shaped items in place.
The first thing I did when we brought home our Stelvio was remove the roll cargo cover and parcel shelf from the lift gate preferring the station wagon configuration. These are stored for the future new owner in the event we upgrade to the next Stelvio in the future. Also the tie downs are stored in a padded bag behind the removable side panel- I wanted a flat floor for our Rottweiler.
The shape, size, low liftover height, and folding seat options make for a very versatile vehicle that meets our needs perfectly.