Yes I know there are other maybe neater solutions to this age old problem of broken lugs etc as the units are now unobtainable, but I offer this to others as a possible answer. I used alu sheet (2mm) from
here which is always useful for making up brackets plus some
stainless self-tappers. A quick and simple job. If I need to change a bulb I'll remove the screws from the metal not the plastic lens. Close the tailgate and of course the brackets are not visible.