You should never represent yourself in a criminal matter no matter how small the crime. If you can't pay for a lawyer the Court will appoint one for you.
A local experienced criminal defense attorney will know the answer to your question "Was this actually criminal trespassing?" and SO MUCH MORE which is why you absolutely need a lawyer. Your lawyer will know how to prepare the case for trial and how to make the most compelling arguments.
If you can't afford to hire a lawyer, the court will appoint one at no cost to you.