Might check with your insurance company to see what the extra amount would be for the 4 vehicles.. With my insurance company (USAA), when there's more vehicles than drivers, the extra amount isn't that much for the extra vehicle. The rates are based on mileage driven and value of the vehicle at risk..

When you designate the lowest value vehicle as your primary daily/work driver and put the extra vehicles for pleasure use only, it seems to drop all the rates.

e.g. my wife's '88 camry is her daily driver and her new '06 Pruis is for pleasure use only.. We decided to keep the old vehicle since she has to leave it in a park and ride lot for her work commute and comes in handy for hauling dirty stuff.