I recommend that you contact the criminal lawyer who represented you on the initial sex charge to discuss your exact sentence. From what I read in your information, you will be on 2 years probation. If your probation is not over, you should have that time to pay the restitution and fines. If you need more time, you can tell your probation officer. If they can't do anything about it, you can attempt to get back on the judge's calendar to address the issue.
I am a Florida criminal lawyer, but probation issues tend to be similar. In order to sustain a violation of probation, the violation must be willful. If you cannot afford to pay, the chances of your not paying being deemed willful are lessened.
Contact a criminal lawyer in your area to discuss your case further.
This answer is for informational purposes only. This answer does not constitute legal advice, create an attorney-client relationship, or constitute attorney advertising.
It is not uncommon in Wisconsin for terms of probation to be extended when someone cannot pay restitution, fines, or costs in the original term. This does not happen in all cases, however, so you will need to contact a qualified defense attorney in your area to determine exactly how likely it is in your case.