Food truck catering question.

I would like to hire a food truck to sit outside of a customer's location and feed their employees lunch. They have about 50 people, and I'd pay for the whole thing.

I've found some websites that have a bunch of food trucks listed that can be hired out, but I'd rather work directly with the owner of the truck and not through a 3rd party. I have a few questions:

1. Is 50 people enough to have a truck come out (west Houston)?

2. Is there a reputable website that puts the money directly in the owner's hand?

3. Anyone know of any trucks I can contact to ask directly? I'm thinking simple tacos or something like that. With a drink. Nothing too crazy, this is blue collar stuff. Not looking for Indian/Japanese fusion (although I'd be down for that).

Any help would be appreciated!