Business with Pending IRS Voluntary Disclosure Audit

I am considering an LOI going though a voluntary disclosure with the IRS right now. I am trying to think about how to structure the LOI. I know the seller wants a small seller's note since he wants to be paid out as soon as possible to cover the IRS bill when it comes. As a result my thought is a smaller 10% seller's note, but with a standby period of 3-4 years and then putting a large amount of the purchase price into escrow or something to be distributed upon receipt of the IRS Closing Agreement. Curious on people's thoughts/take on this.