Fitted my rear work lamp ...
Bought one of these from fleabay:
24watt LED flood light
and then some 25mm box steel from B&Q for £8.00
and a 12volt illuminated rocker switch from
Maplin for all of £1.79
had some wire at home.
So - soldered the wires to the switch, drilled all the relevant holes in the steel box after cutting it down to size. The hardest part was the cut-out for the switch - has anyone invented a drill bit that will drill square or rectangular holes yet?

Some elbow grease and a file did it though ...
I've left it quite tall so I can judge how much the spare wheel gets in the way - I'll trim it off if necessary, then paint it up. But for now, it works ...
trying for fit:
I'd bought a Kaymar spacer a while back - it came with the side bracket for their extendable lamp - wasn't about to pay another £200 for that
After installing the switch - a test:
It works!!
All fitted - looks OK
and still works!!!
I'll check the throw in the semi-dark tonight and maybe drop it by an inch or two. Pretty chuffed though, for now. The switch isn't waterproof, so I've hidden it behind the spare wheel, facing in towards the door. Should be fairly OK there, for now.