I had an idea the other day for a good way to make money. It probably takes a bit to start up, but is something I think would work quite well. I have not done any research into it properly, but I know where we used to live and where my husband used to work it would have gone down well.
My husband used to do warehousing work and start at 5 or 6am. He usually finished about 2pm. There was a lunch truck that used to come with sandwiches and things at around 12 or 1. Most of the guys went and bought from it. They wished it came earlier as they had been up for so long and by the time it came they were close to home time.
I know a lot of the factories and warehouses there have their staff start very early like that so my thinking is a breakfast truck would be more appropriate, coming around 9am, or when they have their first break.
You would need to truck with the companies you wish to visit to see if they will allow it. You would need a check decked out with refrigeration and cooking utensils and equipment. You would need to find out what they would like to eat, what is easy to have prepared, OH&S laws, insurance etc...
So it is not something you could start quickly and easily, but it an idea that might help someone.