nginx location block serving two request paths, one needs an extra header

I have a single location block with many configurations, which acts as a proxy cache for multiple APIs. One of the APIs requires one additional config:

proxy_set_header  Content-type "";

I can't seem to put an if statement anywhere and am aware that if statements. in general and especially in location blocks, are bad practice. Regardless, it's "not allowed" anywhere I've tried.

How can I add this additional config without creating a completely separate location block and cache just for this one API?

This is essentially what I want to get done:

location /cache/  {
  proxy_http_version      1.1;
  proxy_cache             CACHE;
  proxy_cache_valid       200 302 5m;
  proxy_cache_key         $host$uri;
  proxy_cache_lock        on;
  proxy_set_header        Connection "";
  proxy_set_header        Authorization '';
  proxy_hide_header       x-amz-meta-server-side-encryption;
  proxy_hide_header       x-amz-server-side-encryption;
  proxy_hide_header       Set-Cookie;
  proxy_ignore_headers    Set-Cookie Cache-Control;

  if ($request_uri ~ /cache/device) {
    proxy_set_header      Content-Type "";
  }

  proxy_pass              http://upstream;
}

(See the if statement.. i don't know why i cant bold that)

Thanks