"...using a vehicle with a hidden compartment with knowledge that the hidden compartment is used or intended to be used to facilitate the unlawful concealment or transportation of a controlled substance..."
Well, if this guy really did not know of the compartment, or that the compartment was intended for controlled substances, then he is not guilty. How does the prosecution prove in court that he knew it was there and what it was for? I guess they could have written or audio evidence of him talking or emailing or texting about it. How does the accused disprove the assertion that he knew? ["He knew." "No I didn't." "Yes you did." "No I didn't." ...]
This is a really scary part to me, the "thought crime" (as Heavies commented):
The Ohio law passed last year prohibits, “designing"....
So if you have a piece of paper with a sketch on it, or they record an audio conversation wherein someone discusses creating such a compartment, you are guilty of a crime... a felony crime at that.