Do you have to be a coffee shop?
I assume there are some stalls within the market which are doing well? What are they?
If there are no stalls within the market that are doing well then I doubt you could find anyone to advocate anything other than cutting losses.
If, however, there are stalls doing well, then lets take a look at them. What are they selling? Who are their customers?
Another thing every business should ask itself is "Why am I going to use you?"
One of the people I work with has a wife that paints nails, and he asked me to help as she doesnt get much business. I asked him, "why would my wife use her vs all the others on facebook offering the same service?" His reply was that, "she's really good." I asked him to come back to me with a list of all the competitors that said they were not really good.
Why would I choose you?
The answer can be anything.
Sometimes we find ourselves so far down the rabbit hole we forgot where we started. A series of decisions may have lead us to a point where we consider our options within such a narrow field, because we are defining it by the situation we are in right now. But we can always start from scratch.
At the moment it sounds like the only asset you have is the pitch, not a coffee stall, so lets look at what you could do if someone offered you a pitch in this market for free.
Remember, your spending to this point is a sunk cost - you ain't getting it back just because you spent it. Forget it. Move on.
It might sound hard, but you need to, at least for clarity of thought.
You are saddled with a burden because of the lingering thought of your outlay. forget it.
Now you have an opportunity.
Someone has just given you a pitch in a market free of charge to do whatever you want with! Be excited! Get thinking, then get to work!
