I just happened to think about which side of your trailer or truck your service window should be on. In our area a food truck or trailer can set up on public streets and serve food, but only to the curb side of the vehicle. So if your window is on the drivers side you’d have to serve to the street, not the curb. Unless you parked facing the wrong direction. That’s why some builds have a service window on both sides. But a word of caution on two service windows: our state fair charges by the length of the vehicle on the side where the service window is. Two windows (one each side) you pay double even if your not using one. three windows both sides and end you pay X 3. Just a thought but another good reason to check where you might be vending and local rules before you pick your service window side.
jack