I love out-of-the box thinking. If it were me and I had the budget to consider your first proposal of combining an 80 & 100, I would first go down the path of maximizing the IFS. My personal preference would be a solution like Marlin Crawler’s RCLT. And I agree with the above statements about maybe BP’s not being as tunable as King’s or Fox. I would also go down the path of the Canguro build with a body lift and larger tire size. Then try to get someone to make a fiberglass fender to cover properly at the front.
Edit: this is actually my personal long term goal as well