After tenant move out: Payment plan for unpaid rent

[Dee Sivad]

In Contra Costa County, CA.   There's a long story I won't go into here, but I want to set up a payment plan with an ex-tenant in lieu of going to small claims.   If anyone's done this, please respond -  how did you go about establishing the terms of your plan, and how did it work out for you?

If the ex-tenant signs a binding agreement and defaults, can I use that agreement to hire a collection agency?  (Yes, I realize they may only collect pennies on the dollar, or nothing)

Thanks.