I have to select a predetermined percentage.

The LLC should have Right of first refusal to purchase at a predetermined price or appraised / fair market price so siblings don’t decide to “value” it at $5M and then force a sale just to get cash.

Is it reasonable to think I can do a FHA with my lender at the maximum and have the seller carry the difference and make interest only with a balloon payment in a predetermined amount of time. 

Most of the time the terms are already predetermined, but I guess everything is negotiable depending on the down payment and such. 

Instead, you could reinvest that entire $100k in an Opportunity Zone and avoid the tax.It's not as simple as just purchasing property in predetermined OZs though.

The price you can pay is pre-determined by the location and condition of the house as well as your eventual strategy for the property.

The best you can do is estimate, and plan on holding for a pre-determined length of time.

You mentioned the need to fly out to your market and I'm curious how often you schedule these trips and if they coincided with certain predetermined milestones.

Pick out some predetermined fixtures, paint colors, flooring, etc.

A good GC knows how each step needs to be done and can ensure the work is done to your pre determined standards.