This happened to two places on the rear of my '02 Journey, DP. I'm watching the front grill carefully but so far it's holding well. Two of the three places were held on only with epoxy. The big wrap around on the bottom rear of the RV also has 4 big bolts along the sides. But the middle part was floppy and rattled while driving.
What I did was use flathead 6-32 stainless steel screws and self locking bolts. The reason for the small hardware is that the fiberglass pieces aren't all that heavy, the smaller screws should hold them fine for years, and if there's an accident, the fiberglass will be pulled off the screws easily enough that the fiberglass isn't too badly damaged (so I wouldn't have to replace an entire molded fiberglass piece - an expensive proposition). And finally, the screws are so small, and flush with the surface, that they're darn near invisible. And a dab of paint on the screw heads would make them totally invisible. I don't bother with the paint 'cus I can't hardly see them as it is.
Here's my blog post with some pictures of what I did to avoid having to try to get that epoxy system to work over the long run:
Floppy fiberglass body pieces repaired...In fact, I didn't do anything with the epoxy, just drilled holes for the stainless screws right through it.