1)Check the definition of business use class that your auto is rated under. In many cases, contractors autos are rated for commercial use when many, if not all, may qualify for the service use classification. Since commercial use is generally much more expensive than service use, correcting this mistake can lead to substantial premium savings.
2)The higher the population of a rating territory, the higher the auto insurance rate. If your office or yard is in a highly populated area, but you work mainly in outlying suburbs/rural areas, you might want to consider garaging them in the outlying areas if convenient. Doing so might result in a major physical damage premium reduction.
3)Older field vehicles are sometimes taken out of service and used for purposes other than those for which they were originally intended, such as light hauling around the yard. An insurer may be willing to grant a rate reduction based on the reduced exposure.