Will Bondo adhere to metal treated with phosphoric acid?

I have corrosion and pitting on the steel around the rim of my windshield. I removed my windshield and painstakingly removed all traces of urethane adhesive and original paint and primer. I have it fine-sanded to the point that there is some shiny bonding surface to speak of throughout the perimeter, and then I: -- picked the excess rust out of the pits that occur throughout the top edge, and -- treated the entire perimeter with phosphoric acid, and -- picked the excess iron phosphate out of the pits after that, and -- fine-sanded the surface once more, and -- wiped the fine dust away with isopropyl alcohol. I still have black iron phosphate on the surface of the steel within the pitted areas. It seems that only a Dremel will clean it up any better, which would take some time if I even had one. What I have now is supposed to be good enough for applying spray paint and indeed I have had good results with this as a paint prep. But Is it OK for Bondo? Has anyone else out there done so with knowledge of the results? The manufacturer says to apply to bare metal on the package. I'll try their hotline and see if their advice is better than foreigners reading off a 1-page FAQ sheet.