I've made up a rear cargo storage area, I'm still refining it but the main sections are there:
Milk creates replaced with proper storage containers that have been carefully selected for their size to fit in and to what they're carrying.
Light for night time.
The most has been made of all storage areas, these are behind the rear seats and fit in really well. Then came the walls of the setup and this has added a lot of easy organisation of the whole thing...
Just about all the tools I need are carried here - jack, handle, block of wood, random bucket of tools containing things like a spare rear bearing and replacement tool kit (custom), deep socket set, tub of high temp grease, G clamp, welding gloves for hot stuff. Then there's my electrical box, socket/spanner set, ammo box of other tools and small air compressor, soft hammer and small mallet.
Dual battery for running the 40L engel - goes well, still sorting out appropriate gauges to watch what the battery is doing. Also this setup allows me to use the cargo area under the floor in the rear of the L series, random stuff gets put in there at the moment.
As for spare drive shafts, they live down the side of the setup on the LHS, I only carry one front and one rear shaft, plus the 36mm socket and 3/4 inch drive breaker bar to do the tough work for me.