It doesn't have to. How good a welder are you? You could reinforce a good area with 1/8" plate curver to fit flush and weld it on with a nut welded onto the back side and recess it into a hole in the B pillar. Weld it on the B pillar and paint to match. It could look fine if you can weld really good. IMO, that would be acceptable as a crash restraint. I would "guess" maybe a 3" x 3" piece of 1/8 plate would be sufficient.