The adjuster bit you mention is often rounded, and the best cure is obviously SS cap head in place of it, the part of the bracket that is secured to the bumper is moulded on, but is still doable, a fix that is just a bit more fiddly.
The side supports at the lower edge of the front wings need to be undone, ther eis usually a 10mm bolt rusted to shit inside the captive nut part, I just gently prised mine off, with a jemmy between the wing hanger part and the bumper plastic piece then re-bent to shape the wing hanger afterwards, I then filed down the edge of the bumper side support so that I can insert a 8mm SS bolt all the way through, and then be able to hold a nut in place between the bumper side support and bumper inner skin.
tabetha