So turns out that the way I made it work was removing all the proxy related options.
server.basePath: "/kibana"
server.rewriteBasePath: true
Which I honestly find confusing, especially when the documentation and everywhere you look for, says you need those too in order to work with a reverse proxy...
Apparently, the code takes "/" as the base path if you don't specify 'server.basePath', which is what I was looking for, having also 'ProxyPass/ProxyPassReverse: / http://localhost:5601/'. This way you can simply access http://localhost
and takes you to Kibana, no need to add all the paths to the reverse proxy...
Finally change 'server.host' to '127.0.0.1' and you don't have to worry about people trying to access kibana through the port, if they come from external connections.
Honestly, I'm a bit mad this case is not considered in the documentation, I feel like a lost more time than I'd like just because the documentation and everywhere I looked told me to use those parameters which aren't really needed.