[darkalchemy]

You quote my post but you aren't using it. I don't use it with cloudflare, but I have been using that config for more than a year.

This line sends all of the query params and adds the ip, just in case, to XBT

proxy_pass http://127.0.0.1:2710/$1/announce$is_args$args&ip=$remote_addr;

I am not an expert with nginx, but I think this line just rewrites the incoming url and does nothing for XBT

rewrite ^(.*)$ $1?ip=$remote_addr break;

since this line is what is sent to XBT

proxy_pass http://127.0.0.1:4000/;

Maybe try getting SSL to works without Cloudflare. Once you have that working move on to Cloudflare.
Hope you get it sorted.