Hi spacerobot,

I am encountering a very similar problem with my nginx/unicorn server with an 11k URI, getting error "HTTP/1.1 414 Request-URI Too Long".

We have also modified the nginx.conf httpd context to include:
client_header_buffer_size 32k;
large_client_header_buffers 16 512k;
Which in theory should be more than sufficient to handle this URI...

Could you please give some more information on what you've modified with Unicorn to allow a larger URI?
Thanks!