SEM MiniMax works well, just make sure that the cartridges flow the mix at the proper rate.
https://www.ebay.com/itm/395494860409?
It would help if you could bring the pieces closer together somehow-even with gorilla tape and do the repair 1/2 at a time. Or better yet, remove the bumper cover and do it off of the actual metal impact bar, then reinstall. I recently had to do this with a r129 that had damage to the lower integral valence/spoiler.
One of the comments to the ad is interesting, suggests using drywall mesh tape behind the repair. Great idea.