HAWT vs VAWT, just FYI. It may be that any incidental flow off the towing vehicle or continual side wind would render the VAWT unusable. Regardless, sustained wind of 60+ MPH will render everything conventionally built into pieces in the first day of use, if not sooner.
If I was looking to get some power out of wind when my vehicle was in motion, I'd be experimenting with small-bladed fans with a permanent magnet DC motor. A few of these placed in specific areas on the vehicle might make enough power to TEND a 12v SLA battery.