There is a company that has a lot of free information on how to set up a hot dog cart business.
They make dozens of different superb quality stainless steel dog carts and food carts and ship them everywhere on mainland USA for free.
They are near us in California so we went to see how they are made which was amazing, they actually have a model called the North carolina and another called the Carolina on their web sites.
We bought one of their Idaho Models in 2002 and a smaller one called the Phoenix modelin 2003. They custom make them to order once your health department approve the Diagrams. We bought ours for huge events, swap meets and corporate parties as they grill,steam and boil over 1000 hot dogs per hour.
They offer lots of free information on rules and regulations and how to set up.
By the time we had read all of the free information, video's, pictures and diagrams my partner and I felt like hot dog carts experts.
I wished we had found them before we bought our first cart from another firm on the East Coast six years ago, the health department just laughed at it and sent us away with a list of 11 needed, and expensive modifications before they would look at it again.

We did'nt let them look at it again, we took a total loss and virtually gave it away at the very swap meet we were supposed to be selling hot dogs at.
After that major embarassment We went to and they coached us through the diagram plan approval process which took 3 days so we had plan approval before we even ordered the cart.
Check with your Health dept first as a lot of carts don't pass the health department inspection. Find out their main requirements take guidance from the real experts and then you can choose what cart best fits your use.
If you buy a pre owned model make sure it has passed the Health Inspection in YOUR county before as it will be grandfathered in under older and less stringent regulations.
Good luck