Just having a think about weight savings here...
Setup 1. Side-by-side drawers + fridge cage + (maybe) fridge slide
The ubiquitous titan drawers and wings ~80kg (pretty standard).
A fridge cage is another ~15kg.
So we're at 95kg if you use the (crappy) built in fridge slide.
A decent slide for 15kg and you're pushing a
110kg storage solution around. Your fridge is sitting pretty high, so you might consider a drop slide instead for another 40kg making a total of
135kg
Setup 2. Drifta vertical stacked drawer, fridge box combo ("Wagon #6)
Ok so if you scrap that setup, you could have an all-in-one Drifta stacked drawer setup with the fridge on the left, which included everything above and kept the fridge at a nice height. My used set was
67kg, but if you want the proper setup with a false floor and wing kit, you're looking at ~
80kg
Setup 3. Qubelok shelves, fridge platform replacing middle row seats
My cargo setup is ~22kg
My fridge platform is ~4kg. That's just one side, so if you go for both sides you're looking at a total of about
30kg for storage.
The middle row seats have to come out at ~22kg each, saving a total of ~45kg.
(This storage solution is actually "free" payload in a sense)
So if we compare my current setup to setup number 1, we've saved from ~
125-150kg
If we compare it to the drifta setup we're saving ~
80-95kg
For reference, 150kg is a QUARTER of the 600kg payload available on these wagons.
I've also gone from a RTT at 80kg to a swag at 20kg, saving another 60kg
I believe payload in Australia doesn't even include a full tank of fuel. So another big chunk gone there.
A steel bullbar weighs 80kg.
A "lightweight" roof tent on a "lightweight" aluminium platform rack will run you ~100kg easily.
Add water, food, beers, camping gear, 20kg of dual battery, a 15kg dog, a 30kg winch, a 15kg hi-lift, maxtrax.... Rear bars, sliders, steel bash plates, cast iron ovens, .... The payload just disappears before you've added two humans at another 150kg.... No wonder we are all running around over GVM!
I'm not what else you could use. Some kind of polycarbonate panel would be heavier.
Perhaps thin gauge aluminium sheet would be lighter for the walls, but it would be difficult to bolt things to while keeping it from wobbling all over the place.
There's honeycomb composite panel materials out there but you'd spend a fortune to save just a few kg, and again not as simple as just driving a screw into for mounting a fuse panel, compressor, tool holders etc