That's exactly his plan.
But at some point the IRS will say no, they don't have to accept his payment plan.
If he owes $20k a year in taxes but only pays $6k a year on his payment plan that's $14k a year being compounded on a debt he can't get rid of, owed to people who can take your house and use violence against you.
I don't know how he sleeps at night.
He won't be giving the itemised accounts to the IRS but he will have itemised accounts somewhere, this is what his accountant should be doing. It's a necessary step to calculate how much he owes the IRS.
But I am a Brit, your system might be different to ours but it can't be that different. Somewhere there is an itemised accounts for his business and I'm guessing if the IRS did investigate he would need to hand them over.