I wish I had better news for all you dealers looking to find every loophole in life. The reality is that every Personal Auto Policy has a whopping exclusion for commercial-type exposures. This means that the second that an accident happens, ownership of the vehicle will need to be proven.
The purchase documents will show that the vehicle was purchased by the dealership. (If it was purchased by the dealer as a private party, then the dealer as a person would have had to pay the sales taxes and DMV fees.) Once a dealer is established as the owner of the vehicle, a Personal Auto Policy will exclude all claims related to that vehicle.