try this....
Jose: I was going to do this, but never got around to it.
Get a circular steel plate cut about the diameter of the inside of the spare wheel, drill three holes for the mounting bolts, have a short piece of steel angle welded to the plate, drill a hole in the angle for the light stem. Paint the plate.
Remove the three nuts that hold the spare tire in place, slide the steel plate onto the the bolts, replace the bolts. Then mount the work light onto the angle piece, and wire it up from behind the wheel. Zip tie the wires onto the arm of the carrier, run the wires underneath and up to the front panel and BAM!
Points to consider: when mounting the angle onto the plate, put the work light onto the angle so you can see where (on the round plate) is the best location for the light, so that it can swivel etc.. without hitting the tire. this may mean that the piece of angle may need a long leg, like 3 or 4".
You also might consider using some rubber washers in the mounting, so things don't rattle.
Obviously, the tire cover will be useless. Also, when wiring the light, use demountable electrical fixings, so you can temporarily unplug the work lamp if you need to pull the spare (and the plate) off.
If you can make sense of this message, you're smarter than I. Even though I don't own it anymore, I still have a bunch of projects for that 88"
DW