Optimal structure for a HNW family investor

Hello SF Community,

I am speaking with an extended family member who is a HNW individual considering backing me in a future acquisition in a $3-10M EV range. He wants to provide terms that is somewhere in between a favor as a family member and a commercial investor so he receives a reasonable return. Optimizing for taxes is very important to him.

I am trying to figure out structural ideas that would satisfying the following, assuming no other equity capital:

1) Allow me to retain the majority of the economics and decision making (>70%) with a limited or no cash contribution on my part.
2) Not require the business to ever be sold should I want to keep running the business in perpetuity.
3) Ensure I am repaying him his "principal" or initial proceeds as quickly as the business can manage in a healthy manner.
4) Limit his exposure to ordinary / pass through income and maximize his capital gains.

I am probably being over simplistic here. But what about an LLC or S-Corp, taxed as a partnership, where he owns a small amount of the equity (5-20%), and the bulk of his investment is a promissory note with an agreed timetable and ability to prepay as business can manage. Then create some kind of "agreement" that I repurchase of his LLC shares in the future at a premium. This would allow me to repay his principal back through the promissory note, and provide upside generating capital gains tax treatment for repurchasing his shares over time.

Appreciate any feedback + considerations to my simple idea and other creative structures or ideas that would helpful here.

Thanks so much everyone!