In my push forward to make sure that I have all the brackets and little trick things welded to my cage before I remove it to complete the welds and then prime and paint it, I made a fire extinguisher mount. This mount will bolt to the cage (on bungs that I weld on) and the extinguisher will clamp to the other mating bracket with hose clamps.

After making some patterns I used some 3/16" plate to cut my parts from.