15 Passenger vans can be very dangerous mostly because they are used sporatically by people who have very little experience on this type of vehicle. If you look at the statistics, the vast major of accidents with this van happen on fieldtrips and church outings. As they are driven by teachers and faculty that have average driving skills and no additional training. These vans are very top heavy and can be unstable if not driven correctly, so I would suggest that you look into some type of advanced driving course to teach you how to better handle the van before you purchase one.
The problem is the height and the length of the frame and not the number of seats or people inside. I would agree that if you have the option, looking in to a 12 passenger van is safer and possibly more economical.
We had a Ford Club Wagon when I was growing up (family of 7) and it was great. It was designed to hold 8 people, but it had room for another seat in the back. We drove it across the country and even hauled the horse trailer with it. My dad finally retired it after 300K miles when the all the kids moved out and the extra space was not needed anymore. I am not much of a car person, but I do know that the vast majority of the public transit vans and the smaller campers are on Ford chasses.
Yes, you do need a Class C CDL to drive a 15 passenger van in Colorado. I am not sure if that applies if you only carry your family, but it is probably not very realistic to think that you will never have someone else in your van. Plus, the purpose of the extra license requirement is to require the extra training that is essential to keep these van safe.
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