I struggled with this same problem many years ago. The frustrating part is that it is difficult to find an epoxy that will bond well enough to the urethane fascia. The act of installing the rear fascia usually requires some rough handling while pulling and popping the threaded studs through sheet metal brackets. Overtightening the nuts will often pull the studs loose where they've been glued with a weak adhesive. Lastly, the rear fascia, being made of urethane, has a lot of flexibility, and moves with changes in temperature - these things ask a lot from your adhesive.
Purchase the stainless replacement bolt plates. After you've ground out the old stud, clean the area very well with acetone, and apply GFlex epoxy according to the instructions. I am convinced there is no better epoxy for your purpose. It is not cheap, but it works well on plastics, as well as gluing dissimilar materials together. You can get it online, or at any West Marine retail store.
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