Wow, did I luck out! Before taking the plunge and spending $120 for a new part, I was making one last search for a used headlight bracket/panel/plate and found this thread on google (though hadn't noticed it previously while on the site).
Montmil's mounting solution is briliant. Mounting new posts on the headlight mounting ears will allow me to cut off the remaining post. The lower half of the bracket was previously either broken off or cut off below the ears and subsequently re-welded back together.
Picture is from before I lost the post, but the newly located posts will work great with the Givi windscreen.

I'll still need to fully remove the bracket (all quick except for the brake line) to sand and paint, but should be up and running in days for little expense, instead of waiting a week or so for an outrageously priced piece of sheet metal.