That is pretty much what I do.

Tell them to minimize penalties and interest, pay as much as they can by the due date.

I usually tell them if they are able to pay off State, do that and then they only need to deal with one tax agency for what they owe.

Let the client know what the IRS will tell them:  If they can pay it within 4 months (120 days), the IRS will pretty much just say "okay".  

If it will take them longer than that, they should set up an Installment Agreement and then send them the links for that.  The lowest cost is to set it up online, and with automatic withdrawals from their bank account.

https://www.irs.gov/payments/payment-plans-installment-agreements

https://www.irs.gov/payments/online-payment-agreement-application