If you have any longer, loose hair wigs or wigs with a VERY simple style you can do in the hotel room, I would also recommend loosely braiding them to prevent tangling. That's how we transported my ex's Sesshoumaru wig and my Kagura wig in the trunk for a seven hour drive. My Kagura wig was just a simple a side bun that I had already practiced and knew would only take about fifteen minutes to restyle so I decided to braid the wig and redo it at the con to save myself the hassle of de-tangling or fixing up any possible mishaps that could happen to the style in transport. It also saved room since our back seat was full and the only place for our baggage and costumes was the trunk. For more complex styles, you can leave the wigs on an upright wig head in a box, ask one of your passengers if they mind holding one in their lap, or stack them gently in a box like JasonTerror said.
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