As one who practices in the Miami misdemeanor courts regularly, I can tell you that most judges are understanding when it comes to defendants' inability to pay court costs. Nobody is going to put you in jail simply because you owe the court or probation department money unless you clearly have the ability to pay and are just refusing. You may want to ask, in lieu of a payment plan, that the court convert all remaining monies owed to a criminal order and terminate the probation. This way, it will act as a simple financial judgement against you and no one will pursue payment unless you eventually regain the ability to pay.
Violations of probation must be willful behaviors. Not being able to afford the fees and fines is not willful. Your having completed all the other conditions is evidence of your desire to complete everything in itself, but it would help if you had some documentation of your income and bills just in case. Therefore, you should deny the violation as being not willful. If a lawyer is to be appointed they would be appointed at that time. If the judge wants to just go ahead with the hearing, it means he does not expect to give you any jail no matter what, so go ahead and ask for a lawyer and if denied, explain your circumstances.
In any event, you should express your desire to pay it all and explain you'll require some time in order to do so. The judge may set a payment plan or even waive the outstanding costs of supervision (probation fees) if he or she feels like it (less likely with state budgets being hit and judges taking pay cuts).
Keep doing what you're doing and it will work out alright, in my opinion.
In 28 years of criminal law practice, I have never seen a judge put someone in jail for failure to pay fines/court costs, provided the is no ability to pay.
Frankly, in County Court it is common practice for a judge to either extend probation or transfer the remaining balance to a collections court division in these circumstances.
You would be well-served appearing in court ready to explain (and prove) your financial hardship. I think you will be OK, provided there are no other violations.