What I was thinking was what if we had an agreement to split the Option Consideration from the new buyer at some pre-determined ratio?

This is the way car lease agreements are done, you give some money up front, you pay the lease, and at the end you have the option to purchase the car for a predetermined price.

If I wasn't able to qualify we would sell the home and each take our predetermined cut of profits.

I understand that I'm not getting a 'Deal' in the typical since of the word, but the condition that you find yourself hypothetically in is what opens the option for someone to come in, help you out by letting you stay in your home only as a renter, and negotiating with the bank for a predetermined amount.

Can you show me a legal requirement where a loan must have a predetermined interest rate and repayment terms and where conditional compensation such as % of profits would not qualify as interest?

Once you do that you have narrowed down your list to only those that qualify and you then choose the most qualified.Operating without predetermined strict screen standards is like buying a pair of shoes without consideration of what you intend to ware them for or what size they are.

I want to make monthly payments to them for the desired term and then get the 20 year Commercial Loan to seal the deal at the end of the predetermined timeline at the predetermined price. 

@Julien Anaya - my company offers facilitation services for situations such as the one you described via our online platform - rentback.comOwners (Sellers) access their equity and pay market rate for their home for a predetermined term (sale/leaseback) - house is sold to investor and Sellers become Tenants.

@Kyle Mitchell - Prepayment is can be predetermined for business plan purposes, yield maintenance is an unknown. 

I have a property on sale and have been approached by someone to have a Lease to own (option to buy after 35 months at predetermined today's price).