Wow I wish I had seen this before I dove into my project. I'm retro'ing in 2.5" projectors with Pivot Profile halos (a LOT of work...). Making progress and running into same issues you were (i.e. disintegrating wiring). This is very inspirational and definitely gets me excited about finishing my lights.
Those look great. Just a thought. Retrofitlab.com sells just a metal centering brackets that replaces the bowl for around $30 if I remember right. Your headlight might be able to be mounted to these some how.