Thanks bronco! I actually decided to be brave and try plastic welding for the first time! Bought a cheapo from harbor freight for $15, and cut some polypropylene from the stock airbox I had lying around which was nice and thick. Used the mesh that came with the kit to reinforce the weld. It's stronger than the entire tab now! I might have to go back and add some braces to the bracket since I can literally weld to almost anywhere on the headlight. Not the best looking solution, but it works!
Tomorrow, I'll re-wire the harnesses so I can test them out of the housing and point them in. Once I have a baseline for what angle they need to be in, I can finish modifying the housing to make them work and re-seal them finally!