How can the professional representative become a “future expense” and have our fees factored into the Offer?

Our fees are an allowable expense. However the Offer calculates future income, and we do not take on representation without being paid up-front! So, in order for us to be a future expense, we need to be paid in a way that the taxpayer will have to repay it later, preferably after the Offer is over with.
One way to do this is if the taxpayer borrows the money to pay our fee from family, and then signs a note with that family member that it will be repaid after the Offer-in-Compromise is settled over 24 months. This creates a future expense for the taxpayer that is allowed.