I strongly suggest that before you proceed any further with your plans to build this food truck, you should first consult with your local government agency that regulates food trucks and study the code requirements. Ask for a check list also of the things the inspector will be looking for. If not, you will be spending a lot of time and money building this truck only to find out that you're in violation of the health codes governing food trucks. An example of a potential problem would be whether the food handling equipment are NSF grade or not. Another is where you are going to store the vehicle and supplies. Here in California you have to have an approved commmissary. And yes, you'll need a health permit. If you bring it in for an inspection and it doesn't pass, you'll have to pay a reinspection fee each time.