Getting internet to a protest

Solution 1:

whether this would work

Depends on what you make of this; you could get it to work, but how well?

... 600 meter long street or a 40,000 square meter park ... a TOR node ... thousands of people ...

Passing all data over a single point will cause some bandwidth problems, you'll probably need more.

how you could deliver

There are multiple ways; you could reuse existing infrastructure which is proven to work, although you'll have to breach the ISPs equipment or get an agreement with them. Failing that, some form of cable / radio communication has to be introduced that would be sufficient for social media traffic.

Then, the question is how you will make the networks and how you will interconnect them. How many hosts per network? How many networks per street? How will you connect the networks? Where will you place the necessary servers (DHCP, ...)? Where are your points of failure? Which streets will use more bandwidth than others? If one street starts mass reporting, will the network die? ..?

There's a lot of thought that can be put into this.