Here you go @SouthernComfort a couple of pics, green arrow shows the door seals around the edge to stop water/dust etc from entering while the flap at the red arrow acts as the cap and seals the inlet, there is also another flap about 40mm inside which is a restrictor if you try to put a larger nozzle in, if you can't push this one open you can't get the juice in...the blue arrow is where the drain is for spills, it comes out at the bottom of the wheel arch, a spill means it stinks for ages.............
@johnnywall At 66 I'm still fit and able, possibly because I only lifted things like jerry cans up high as a last resort...........much prefer a pump, hand or electric but certainly not a stirrup pump, hell that is painful for sure and since I'm getting lazy and hate pulling inside linings out I will more than likely rig up a 12v fuel pump to move the stuff, like you I only carry a full jerry when I'm heading into out of the way areas.... don't like to rely on places out there, no fuel or blackouts can often be the case...... a Jerry should give me 120kms towing....
If we head out to Cooper Creek I will fill up a jerry or 2 at Eromanga in case I want to do any extra running around then refuel at Thargomindah, fuel at Nocundra Pub while available would have me worried as to age and price..................... I will get a cap though.