I like your reduced menu. That should make things more manageable. I can understand your fears about "hurting your wallet" on wages. However, you could look at this "first time festival" setup as an advertising expense if it ends up as a negative cash flow.
Sales at festivals are a bit fickle. It can depend on the type of festival (i.e. who is attending), number of competing food vendors, length of festival (days), total attendance, well you get the picture.
Our approach to a festival that we have never attended or are unable to obtain reliable history on from sources is to to use the SWAG method (Scientific Wild A$$ Guess
) for expected sales and use our results to decide if we want to do it again and adjust accordingly. We always look at a new venue as a learning experience and don't necessarily use profit expectations as a criteria to decide to try it out. If it is profitable then we celebrate and repeat.
Hey if everything was already known......things would get pretty boring.
I believe you will find that Vending is a different animal than Catering, even though there are similarities.