You can email Chief Nathanson and pose your question directly to him. I do so with a question in the past and he did an excellent job in addressing my concerns when he had the time to do so. His email address is
enathanson@ladylakepd.org.
Having said that my opinion is that if the seal of the cap is broken or the cork is popped, it's an open container. On the other hand if you have it put away in the back of the cart and inside a bag or cooler, it's unlikely that you would get into trouble under normal circumstances since you can't accesses it (unless you're a contortionist) and an officer would have no probably cause to look for it unless you're driving erradically or were involved in an accident.
Again I'll state that this is only my opinion. Probably best to avoid carrying any alcohol beverage that's already been opened and avoid ever having to find out!
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ARE VILLAGERS OLD OR ARE THEY RECYCLED TEENAGERS
At my age rolling out of bed in the morning is easy.
Getting up off the floor is another story.
"SMILE... TOMORROW MAY BE EVEN WORSE!"