Sagging rear bumper (Tourer) cure?

[MissMoppet]

For some years I've put up with a drooping rear bumper on the offside but having for the first time removed it last weekend I see the problem. There is one self tapper that should screw into the usual spring clip slipped onto a bracket but the bracket has gone.
The only cure I can see - till someone tells me otherwise - is to remove the bumper again, drill a pilot hole into the metal, then use a 50mm self tapper straight into the bodywork. All the four torx headed bolts are present along the top lip of the bumper underneath the protective panel but maybe some of the combs have gone on the side.