Competition is very stiff and you really have to stand out in this town to make it work. A couple of years ago we had several excellent carts in our local pod, and then a gyro cart moved in. The food was terrible, as they were buying the cheapest ingredients they could get and exercising zero quality control. I tried to tell them that they were competing with some folks who were putting them to shame and that they needed to up their game if they planned to stick around. They basically told me to fuck off. They sold the cart within three months.
Be careful with your sourcing of the truck/cart itself. As far as I know, they’re all custom builds, so you’re either going to have to contract for someone to build one for you or buy a used one that happens to have the equipment that you need. My favorite baker tried to start up a food truck, had a business plan and a vehicle, and the custom builder took her money and never gave her a truck. (Well, technically, after 6 months of delaying and asking for more money, he did give her the truck, but it was so broken that it didn’t make it to her home and she had to pay for disposal. Wiped out her entire startup fund and she had already resigned from her day job. It was awful.) Even outside of outright fraud, I have to imagine that fixing either the automotive equipment or the kitchen equipment becomes more complicated when they’re combined, and anyone willing to do maintenance or repairs will be rare and expensive.