I'm not finished with my setup, but it is working well enough that I only expect to tweak it, not start over. I started with 1/2 sheet of plywood and bolted a 50 gallon storage box from Walmart to it. The plywood keeps it from moving forward or to the sides and will give me multiple mounting points for anything that I decide to add later (I haven't been carrying my PullPal winch anchor, but I might start - there are not many trees here in southern Baja).
It holds a tone of stuff and even with only one strap it doesn't during moderate offroading. I'm sure it would move during a jump or rollover, so I'll work on something else later. I would just run a strap(s) to the rear tiedowns, but the bed extender is in the way. In addition to this box I have a bug-out bag and a fire extinguisher under the rear seat.
As far as extra fuel goes, like all SCrew owners, I store an extra 10 gallons in here:
Here are some pictures of the gear I carry on every trip. Two of the bags are tool bags and the rest contain a combination of gear from my Jeeping days and a few new items for the Raptor.
I decided to drop the HiLift jack from my gear and replace it with these LiftTrax.
LIFTTRAX I haven't used them yet, but the concept seems sound.
I haven't used the PowerPuller yet (below), but it made more sense to me for the Raptor than mounting a winch on the front.
The Wyeth-Scott Co. - portable winches | cable puller | come along winches The accessories above are from my Jeeping days when I used my winch frequently.
There are more rocks than trees where I'm at, so sometimes the chain is needed as a winch anchor point. It is a bit heavy, but a winch w/o an anchor point is useless.
I carry a full size shovel and an ax, just in case. They are secured to teh front of the box with QuickFists.
I'm not currently carrying cans of fuel or water, but there is plenty of room for them in front of the box, which is mounted back a ways in order to allow the lid to open without unstrapping it.