I would think it would be more stable than beer since wine/liquor isn't carbed. Therefore you don't have to worry as much about sloshing and blowing the contents out of the cap. I know they make 1-bottle Styrofoam shippers.
Say it's gourmet BBQ sauce if they ask. Wrap or double wrap in bubble wrap. Fill with more wads of wrap and newspaper. Use the ziplock around the wrap if it still fits. Mark fragile all over the box in several spots.
I've shipped a ton of bottles and never had one break on me. Send it FedEx with fragile liquid stickers all over the box. The reason I like FedEx is that they actually take care of the package when they see these stickers on it. I know of some friends that have put in claims with FedEx over bottles and not that much of a pain to get your claims paid. Make sure that you wrap the neck area well with bubble wrap. Also make sure that you use extra bubble wrap on the bottom and top of the bottle. Then wrap around the bottle bottle with extra bubble wrap. Don't use that small bubble wrap but the the one with the larger bubbles. Line the base with packing peanuts and then all around the the bottle.
This may be a bit more expensive but a sure way to keep the bottle safe for shipping. Try to keep the bottle away from the edges of the box.
I usually buy all this shipping material in bulk along with single, double and triple bottle shippers in bulk to save some money.
Tell them that you are shipping expensive olive oil and kitchenware and pay for the insurance. Take a couple of screws and put them in a old medication plastic bottle or vitamin bottle. This will make it sound that that your shipping something else as well.
Here is some pics of a Michter's 20 Yr that I shipped: