Can a vehicle be classed as a workplace?

Yes. Beginning in the 1800s, "hucksters" used to travel, first by wagon and then by truck, through neighborhoods to sell fruits, vegetables, and household goods. Other types of hucksters would sharpen your knives and shears with a grinder in his truck. Also before refrigerators were widely used, the ice man would have a truck with saw dust on the floor carrying huge chunks of ice and he would use an ice pick to cut you what ever size you needed to put in your ice box.

Hucksters continued through the late 1960s in many towns. Larger grocery stores replaced 'mom and pop' grocerers, and as more modern businesses prospered, hucksters went out of business.