Should we work out a payment plan with our tenant?

[Funyon Funyon]

We had a misunderstanding with a tenant (involving a transfer of a lease) and they failed to pay August's rent. (No one and everyone was at fault as it was legitimately a confusing situation.) He has paid all the other month's rent (sometimes a few days late but never more than this.) We all realized the error October 15th and let the tenant know that instead of insisting on the unpaid rent immediately or charging a late fee, we would give them until the end of the month (October 31st) to pay the back rent plus the rent for November. On November 2, we received 1 months rent (so I guess we put that towards Aug outstanding rent and technically he is now just 4 days late paying November 's rent and everything else has been paid) His lease states after the 5th of the month there will be a late fee and after 10 days he will receive a 3 day notice to pay rent. The tenant just sent us this message "as far as the back rent for August I'm not sure how long its gonna take for my case manager to help me but I can also start making an effort to pay it back as well before we have to go to court or anything..... I don't want this to be a long on going problem I just want the issue over with so we can all move forward thank you."  I am not sure what he is talking about re: case manager but would you set up a payment plan for this tenant and just increase the rent for the next X number of months or head toward eviction. The other thing I was thinking of was agreeing to set up a payment plan but requiring him to sign a new/different lease (he came with a lease that is far more lax than the one we usually use.)

Thanks for any insight!