100% Seller Financed Agreements: Avoiding default, not merely defining it

I am in the process of discussing a unique 100% seller financed deal, tied to an earnout. The seller recently signed a large contract that has started transacting, but won't be fully realized for a year. He still wants to exit the business now, rather than wait one more year to sell. He would like to recognize at least a portion of this growth through an earnout, which SBA loans do not allow for.

I could offer at the higher end of market value to be competitive with other offers and still finance the deal. But instead I have offered an up-front under market price for today's value (to mitigate my risk) - tied to an earnout for one year on the growth of that specific contract (at a lower multiple)...but only if the whole thing is seller-financed. To me, the seller only accepts a lower guaranteed price up front if he has complete confidence in the earnout to come.

The seller is interested, but wants to know how we would structure the contract in such a way that avoids default. Typical language would protect him in the event of default if uncured after so many days, allowing him to take back control of the company and the ability to litigate...which never ends well.

Does anyone have suggested guardrails as it pertains to structure, provisions, or language that would aid in the avoidance of default, rather than simply protecting in the event of? I would provide quarterly financials of course, but perhaps some form of seller consultation following consecutive declining quarters? Any ideas are welcome.